Is a 265/75R16 tyre too wide for my D90 without mods?

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D

Dave Smith

Guest

Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
my vehicle to a lot more greenlaning, to get to work safely in all
winter conditions, and also to go on some of my own land. I have looked
through the mags at tyres and it seems the BF Goodrich AT KO's are well
recommended, so unless there's any sage advice to the contrary I've
pretty much decided to get that make. However, what size should I get?
My strictly non-expert instinct is wider is better for ultimate grip, so
I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
still have several unknown questions to be answered :-

a) Will 265/75R16 fit (height and width) without rubbing on my D90?
b) Is there a good reason not to go for such a wide tyre?
c) The tyre is 10% bigger than stock, and one (car) site recommended
against over 2.5% bigger due to the brakes not coping. Is this true for
a D90?

Many thanks in advance for any help experiences, good advice, bad advice
and general abuse to the obvious newbie question :)

Regards,

Dave.

 
On Thu, 10 Nov 2005 08:25:10 +0000, Dave Smith
<[email protected]> wrote:
>
>a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>b) Is there a good reason not to go for such a wide tyre?
>c) The tyre is 10% bigger than stock, and one (car) site recommended
>against over 2.5% bigger due to the brakes not coping. Is this true for
>a D90?

As Far As I know these are pretty standard here in South Africa and
the BFG are known for good milage. (Thats tyre wear, not fuel
consumption).

we only really got the tdi and td5 in 90 format so I am not too sure
how the d90 will handle them. The big advantage of a taller tire is
that it raises the whole wagon which gives you more clearance. It
might slightly raise your overall gearing but I doubt this would be
noticable.

In South africa a lot of off road driving involves soft sand in which
case the wider and taller the tire the better. In the UK I think you
tend to deal more with mud so I don't think the extra width will help
you much?

regards
stephen
 
Dave,

BDG AT = Excellent tyre & give good longevity.

On a 90 I think I am right in saying that 265/75R16s will fit without
any problems, though you will need to turn out the lock stops on each
swivel assembly to stop the wheels rubbing on the radius arms on full
lock.

I was told that 265x75s are more suited to a 110 due to the increased
self weight over a 90. Its all to do with ideal ground pressure at
each wheel - the wider the tyre for the same weight reduces the ground
bearing pressure and therefore the vehicles ability to grip due to its
own self weight.

Further to the ground pressure issue I believe the ideal tyre for a 90
is a 235x85R16. Its more or less the same height as the 265x75 but is
a tad narrower, thus restoring some of the ground bearing pressure.

On a practical note, I have 235x75xR16 BFG ATs and can confirm they
are an excellent all rounder. Depending on your wheels you may need
to adjust your lock stops. Its easy though, from memory about a 3/4
spanner sorts its out.

Another thing people may say is that wider tyres put more strain on
the power steering pump. This is true but the 265 pattern is a
standard option anyway on some Defenders so I dont consider it a
problem.

Just my opinion. Others will perhaps disagree.

Jon


On Thu, 10 Nov 2005 08:25:10 +0000, Dave Smith
<[email protected]> wrote:

>
>Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
>my vehicle to a lot more greenlaning, to get to work safely in all
>winter conditions, and also to go on some of my own land. I have looked
>through the mags at tyres and it seems the BF Goodrich AT KO's are well
>recommended, so unless there's any sage advice to the contrary I've
>pretty much decided to get that make. However, what size should I get?
>My strictly non-expert instinct is wider is better for ultimate grip, so
>I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
>still have several unknown questions to be answered :-
>
>a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>b) Is there a good reason not to go for such a wide tyre?
>c) The tyre is 10% bigger than stock, and one (car) site recommended
>against over 2.5% bigger due to the brakes not coping. Is this true for
>a D90?
>
>Many thanks in advance for any help experiences, good advice, bad advice
>and general abuse to the obvious newbie question :)
>
>Regards,
>
>Dave.

 
fanie wrote:
> we only really got the tdi and td5 in 90 format so I am not too sure
> how the d90 will handle them.

Thanks Stephen. It's the 200tdi that I have. Have I misdescribed my
vehicle when I say D90? I presume that's short for a Defender 90.

Thanks a lot for your tyre advice.

Dave.
 
Jon wrote:
> On a 90 I think I am right in saying that 265/75R16s will fit without
> any problems, though you will need to turn out the lock stops on each
> swivel assembly to stop the wheels rubbing on the radius arms on full
> lock.

Hi Jon, thanks for your detailed reply. I presume turning out the lock
stops will reduce my turning circle a bit, not really too important
though I guess.

> I was told that 265x75s are more suited to a 110 due to the increased
> self weight over a 90. Its all to do with ideal ground pressure at
> each wheel - the wider the tyre for the same weight reduces the ground
> bearing pressure and therefore the vehicles ability to grip due to its
> own self weight.

Interesting, I'll have to do some more investigation into ground bearing
pressure on the wheels. I wonder if our local tyre shop will understand
what I am talking about ... :)

> Further to the ground pressure issue I believe the ideal tyre for a 90
> is a 235x85R16. Its more or less the same height as the 265x75 but is
> a tad narrower, thus restoring some of the ground bearing pressure.
>
> On a practical note, I have 235x75xR16 BFG ATs and can confirm they
> are an excellent all rounder. Depending on your wheels you may need
> to adjust your lock stops. Its easy though, from memory about a 3/4
> spanner sorts its out.

I was just planning on steel wheels, don't need anything fancy. What
wheels do you run?

I have heard that occasionally on full articulation the bigger wheels
can rub, have you raised your suspension at all? And when people talk
about raising their suspension by, say, 2", is that an easy job for an
amateur to perform?

Apologies to reply with more questions but the deeper I delve into this,
the more questions I get, and because a complete new set of wheels and
tyres is not cheap I want to get it right :)

Many thanks for any more advice,

Dave.
 
On Thu, 10 Nov 2005 12:01:22 +0000, Dave Smith
<[email protected]> wrote:

>Jon wrote:
>> On a 90 I think I am right in saying that 265/75R16s will fit without
>> any problems, though you will need to turn out the lock stops on each
>> swivel assembly to stop the wheels rubbing on the radius arms on full
>> lock.
>
>Hi Jon, thanks for your detailed reply. I presume turning out the lock
>stops will reduce my turning circle a bit, not really too important
>though I guess.
Yes it does, perhaps obvious, but the bigger the tyre, the greater its
reduced - ignoring different wheel offsets for different wheels!!!
>
>> I was told that 265x75s are more suited to a 110 due to the increased
>> self weight over a 90. Its all to do with ideal ground pressure at
>> each wheel - the wider the tyre for the same weight reduces the ground
>> bearing pressure and therefore the vehicles ability to grip due to its
>> own self weight.
>
>Interesting, I'll have to do some more investigation into ground bearing
>pressure on the wheels. I wonder if our local tyre shop will understand
>what I am talking about ... :)
I doubt it! Also, bear in mind, if your driving on sand wide tyres
are good, mud and general UK stuff normally requires the tyres to "dig
in" to some degree rather than "float on".
>
>> Further to the ground pressure issue I believe the ideal tyre for a 90
>> is a 235x85R16. Its more or less the same height as the 265x75 but is
>> a tad narrower, thus restoring some of the ground bearing pressure.
>>
>> On a practical note, I have 235x75xR16 BFG ATs and can confirm they
>> are an excellent all rounder. Depending on your wheels you may need
>> to adjust your lock stops. Its easy though, from memory about a 3/4
>> spanner sorts its out.
>
>I was just planning on steel wheels, don't need anything fancy. What
>wheels do you run?
I have a 200Tdi, 90. Mine is currently sat on Disco 1 steel wheels.
They are fine for both sizes of tyre but the offset is not as great as
3rd party steel modulars so the lock stops need tourning out that
little but more. I trial with mine and dont find the turning circle
that much of a problem. I also managed to get 4 wheels for £20 rather
than paying £30 per wheel for new modulars!
>
>I have heard that occasionally on full articulation the bigger wheels
>can rub, have you raised your suspension at all? And when people talk
>about raising their suspension by, say, 2", is that an easy job for an
>amateur to perform?
>
>Apologies to reply with more questions but the deeper I delve into this,
>the more questions I get, and because a complete new set of wheels and
>tyres is not cheap I want to get it right :)
>
>Many thanks for any more advice,
>
>Dave.

 
In message <[email protected]>, Dave
Smith <[email protected]> writes
>
>Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
>my vehicle to a lot more greenlaning, to get to work safely in all
>winter conditions, and also to go on some of my own land. I have looked
>through the mags at tyres and it seems the BF Goodrich AT KO's are well
>recommended, so unless there's any sage advice to the contrary I've
>pretty much decided to get that make. However, what size should I get?
>My strictly non-expert instinct is wider is better for ultimate grip, so
>I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
>still have several unknown questions to be answered :-
>
>a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>b) Is there a good reason not to go for such a wide tyre?
>c) The tyre is 10% bigger than stock, and one (car) site recommended
>against over 2.5% bigger due to the brakes not coping. Is this true for
>a D90?
>
>Many thanks in advance for any help experiences, good advice, bad advice
>and general abuse to the obvious newbie question :)
>
>Regards,
>
>Dave.
>
265/75 is standard fit on later D90s - my 98 50th Anniversary has them.

You will need to reduce your lock and this will reduce your turning
circle quite a bit. I certainly noticed a difference compared to my 84
D90 with 235/85 which personally I think is a better tyre for off road
use.

Your speedo will also be outside legal limits with the taller tyre and
you will need to sort that out. I don't think you have to change the
actual instrument, but no doubt someone more expert than me will be able
to tell you how it's done on a 90.

I wouldn't take too much notice of what you read on car sites. It
doesn't often translate onto Land Rovers.

HTH
--
hugh
Reply to address is valid at the time of posting
 
On or around Thu, 10 Nov 2005 08:25:10 +0000, Dave Smith
<[email protected]> enlightened us thusly:

>
>Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
>my vehicle to a lot more greenlaning, to get to work safely in all
>winter conditions, and also to go on some of my own land. I have looked
>through the mags at tyres and it seems the BF Goodrich AT KO's are well
>recommended, so unless there's any sage advice to the contrary I've
>pretty much decided to get that make. However, what size should I get?
>My strictly non-expert instinct is wider is better for ultimate grip, so
>I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
>still have several unknown questions to be answered :-
>
>a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>b) Is there a good reason not to go for such a wide tyre?
>c) The tyre is 10% bigger than stock, and one (car) site recommended
>against over 2.5% bigger due to the brakes not coping. Is this true for
>a D90?

probably, depends, unlikely...


unless you do a lot of very soft ground then it's too wide, really, for most
off-roading. Anything much over about 235 is wide on a 90. On hardish
terrain you'll not gain any grip, and might even lose grip, due to reduced
ground pressure. Grip ain't all about width - I had 10.5 wide on my 110 and
have 7.50s on the SIII 109, and the latter performs better off-road - the
110 was lacking in grip on firm steep stuff, although it had a bit more
flotation on soft going, I suppose - on marginal ground it maybe wouldn't
have sunk where a narrower tyre would - however the range of terrain where
that'd be decisive is quite narrow, and the lack of grip on firm slippery
stuff was quite marked.

SWB series go very nicely on 7.50s, which are about the same width as a 205,
but taller. 235/85 are a good compromise for a SWB or a 90 - a bit wider
than standard, nice tall profile for better diff clearance, but not so wide
that you lose too much grip.



--
Austin Shackles. www.ddol-las.net my opinions are just that
"For millions of years, mankind lived just like the animals. Then
something happened which unleashed the power of our imagination -
we learned to talk." Pink Floyd (1994)
 
I agree with Austin. Not all that good with metric tyre sizes. I have
31x10.5x15 on my 110 that I use for towing my trials landy, that has
7.50x16's on.

Wide "floats" over softer ground, narrow bites down through for grip.
Depends so much on what you are driving on.

Wish we could have a nice tyre that will work on ALL terrain.

Cheers. Chris.
"Austin Shackles" <[email protected]> wrote in message
news:p[email protected]...
> On or around Thu, 10 Nov 2005 08:25:10 +0000, Dave Smith
> <[email protected]> enlightened us thusly:
>
>>
>>Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
>>my vehicle to a lot more greenlaning, to get to work safely in all
>>winter conditions, and also to go on some of my own land. I have looked
>>through the mags at tyres and it seems the BF Goodrich AT KO's are well
>>recommended, so unless there's any sage advice to the contrary I've
>>pretty much decided to get that make. However, what size should I get?
>>My strictly non-expert instinct is wider is better for ultimate grip, so
>>I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
>>still have several unknown questions to be answered :-
>>
>>a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>>b) Is there a good reason not to go for such a wide tyre?
>>c) The tyre is 10% bigger than stock, and one (car) site recommended
>>against over 2.5% bigger due to the brakes not coping. Is this true for
>>a D90?
>
> probably, depends, unlikely...
>
>
> unless you do a lot of very soft ground then it's too wide, really, for
> most
> off-roading. Anything much over about 235 is wide on a 90. On hardish
> terrain you'll not gain any grip, and might even lose grip, due to reduced
> ground pressure. Grip ain't all about width - I had 10.5 wide on my 110
> and
> have 7.50s on the SIII 109, and the latter performs better off-road - the
> 110 was lacking in grip on firm steep stuff, although it had a bit more
> flotation on soft going, I suppose - on marginal ground it maybe wouldn't
> have sunk where a narrower tyre would - however the range of terrain where
> that'd be decisive is quite narrow, and the lack of grip on firm slippery
> stuff was quite marked.
>
> SWB series go very nicely on 7.50s, which are about the same width as a
> 205,
> but taller. 235/85 are a good compromise for a SWB or a 90 - a bit wider
> than standard, nice tall profile for better diff clearance, but not so
> wide
> that you lose too much grip.
>
>
>
> --
> Austin Shackles. www.ddol-las.net my opinions are just that
> "For millions of years, mankind lived just like the animals. Then
> something happened which unleashed the power of our imagination -
> we learned to talk." Pink Floyd (1994)


 
On Thu, 10 Nov 2005 16:00:07 +0000, hugh <hugh@[127.0.0.1]> wrote:

>In message <[email protected]>, Dave
>Smith <[email protected]> writes
>>
>>Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
>>my vehicle to a lot more greenlaning, to get to work safely in all
>>winter conditions, and also to go on some of my own land. I have looked
>>through the mags at tyres and it seems the BF Goodrich AT KO's are well
>>recommended, so unless there's any sage advice to the contrary I've
>>pretty much decided to get that make. However, what size should I get?
>>My strictly non-expert instinct is wider is better for ultimate grip, so
>>I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
>>still have several unknown questions to be answered :-
>>
>>a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>>b) Is there a good reason not to go for such a wide tyre?
>>c) The tyre is 10% bigger than stock, and one (car) site recommended
>>against over 2.5% bigger due to the brakes not coping. Is this true for
>>a D90?
>>
>>Many thanks in advance for any help experiences, good advice, bad advice
>>and general abuse to the obvious newbie question :)
>>
>>Regards,
>>
>>Dave.
>>
>265/75 is standard fit on later D90s - my 98 50th Anniversary has them.
>
>You will need to reduce your lock and this will reduce your turning
>circle quite a bit. I certainly noticed a difference compared to my 84
>D90 with 235/85 which personally I think is a better tyre for off road
>use.
>
>Your speedo will also be outside legal limits with the taller tyre and
>you will need to sort that out. I don't think you have to change the
>actual instrument, but no doubt someone more expert than me will be able
>to tell you how it's done on a 90.

I have found that now I have the 235x85R16s on my speedo is spot on
when tested against the GPS. I also have the factory fit gear cog.

If you bother to change your speedo its an easy job to do, the gauge
doesnt need to be changed but there is a little plastic cog that fits
into the Transfer Box (at the end of the speedo cable) - They are
colour coded so its easy to see which one you have. I think from
memory they are blue and yellow... or is it green? Personally I'd
just put the tyres on and forget about the speedo thing...But thats
just my opinion.

Jon

>
>I wouldn't take too much notice of what you read on car sites. It
>doesn't often translate onto Land Rovers.
>
>HTH

 
On or around Thu, 10 Nov 2005 19:35:04 -0000, "Bartty"
<[email protected]> enlightened us thusly:

>I agree with Austin. Not all that good with metric tyre sizes. I have
>31x10.5x15 on my 110 that I use for towing my trials landy, that has
>7.50x16's on.
>
>Wide "floats" over softer ground, narrow bites down through for grip.
>Depends so much on what you are driving on.
>
>Wish we could have a nice tyre that will work on ALL terrain.

You'd want a cunning self-modifying tyre, which changed it's tread pattern
to suit the surface and got wider or narrower according to the softness of
the terrain. Ideally the compound of the rubber would vary as well, of
course.

I daresay someone will make one one day.
--
Austin Shackles. www.ddol-las.net my opinions are just that
"For millions of years, mankind lived just like the animals. Then
something happened which unleashed the power of our imagination -
we learned to talk." Pink Floyd (1994)
 
On Fri, 11 Nov 2005 10:01:58 +0000, Austin Shackles
<[email protected]> wrote:

>On or around Thu, 10 Nov 2005 19:35:04 -0000, "Bartty"
><[email protected]> enlightened us thusly:
>
>>I agree with Austin. Not all that good with metric tyre sizes. I have
>>31x10.5x15 on my 110 that I use for towing my trials landy, that has
>>7.50x16's on.
>>
>>Wide "floats" over softer ground, narrow bites down through for grip.
>>Depends so much on what you are driving on.
>>
>>Wish we could have a nice tyre that will work on ALL terrain.
>
>You'd want a cunning self-modifying tyre, which changed it's tread pattern
>to suit the surface and got wider or narrower according to the softness of
>the terrain. Ideally the compound of the rubber would vary as well, of
>course.
>
>I daresay someone will make one one day.

didnt they try that with the new Disco!
 
In message <[email protected]>, Austin Shackles
<[email protected]> writes
>On or around Thu, 10 Nov 2005 19:35:04 -0000, "Bartty"
><[email protected]> enlightened us thusly:
>
>>I agree with Austin. Not all that good with metric tyre sizes. I have
>>31x10.5x15 on my 110 that I use for towing my trials landy, that has
>>7.50x16's on.
>>
>>Wide "floats" over softer ground, narrow bites down through for grip.
>>Depends so much on what you are driving on.
>>
>>Wish we could have a nice tyre that will work on ALL terrain.
>
>You'd want a cunning self-modifying tyre, which changed it's tread pattern
>to suit the surface and got wider or narrower according to the softness of
>the terrain. Ideally the compound of the rubber would vary as well, of
>course.
>
>I daresay someone will make one one day.
Bridgestone and Michelin but they only fit em on F1 cars - and they only
do about 200 miles and they're shot.
--
hugh
Reply to address is valid at the time of posting
 
....and Jon spake unto the tribes of Usenet, saying...


> On Thu, 10 Nov 2005 16:00:07 +0000, hugh <hugh@[127.0.0.1]> wrote:
>
>> In message <[email protected]>,
>> Dave Smith <[email protected]> writes
>>>
>>> Hi all, I have the stock 205/80R16's on my '92 D90. I would like to
>>> use my vehicle to a lot more greenlaning, to get to work safely in
>>> all winter conditions, and also to go on some of my own land. I
>>> have looked through the mags at tyres and it seems the BF Goodrich
>>> AT KO's are well recommended, so unless there's any sage advice to
>>> the contrary I've pretty much decided to get that make. However,
>>> what size should I get? My strictly non-expert instinct is wider is
>>> better for ultimate grip, so I've been eyeing up some 265/75R16's
>>> in one of the LRM ads. However, I still have several unknown
>>> questions to be answered :-
>>>
>>> a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>>> b) Is there a good reason not to go for such a wide tyre?
>>> c) The tyre is 10% bigger than stock, and one (car) site recommended
>>> against over 2.5% bigger due to the brakes not coping. Is this true
>>> for a D90?
>>>
>>> Many thanks in advance for any help experiences, good advice, bad
>>> advice and general abuse to the obvious newbie question :)
>>>
>>> Regards,
>>>
>>> Dave.
>>>
>> 265/75 is standard fit on later D90s - my 98 50th Anniversary has
>> them.
>>
>> You will need to reduce your lock and this will reduce your turning
>> circle quite a bit. I certainly noticed a difference compared to my
>> 84 D90 with 235/85 which personally I think is a better tyre for
>> off road use.
>>
>> Your speedo will also be outside legal limits with the taller tyre
>> and you will need to sort that out. I don't think you have to change
>> the actual instrument, but no doubt someone more expert than me will
>> be able to tell you how it's done on a 90.
>
> I have found that now I have the 235x85R16s on my speedo is spot on
> when tested against the GPS. I also have the factory fit gear cog.
>
> If you bother to change your speedo its an easy job to do, the gauge
> doesnt need to be changed but there is a little plastic cog that fits
> into the Transfer Box (at the end of the speedo cable) - They are
> colour coded so its easy to see which one you have. I think from
> memory they are blue and yellow... or is it green? Personally I'd
> just put the tyres on and forget about the speedo thing...But thats
> just my opinion.
>
> Jon
>
>>
>> I wouldn't take too much notice of what you read on car sites. It
>> doesn't often translate onto Land Rovers.
>>
>> HTH

I found the same going from 205s to 235/85s on a 90. No changes to the
speedo at all.

FWIW, and IA (definitely) NAL, but I don't think there is a legal
requirement to have an accurate speedo. The law simply requires that you
drive within the speed limit - how you arrange that is up to you. I don't
think speedo accuracy (or even the presence of one) is an MoT test point
either. (At least, a search on http://www.motuk.co.uk/ for "speedometer"
gives no matches.) All the stuff about accurate to -0/+10% is C&U regs, as
I understand, and unlikely ever to be tested in the real world.

--
Rich
==============================
Disco 300 Tdi auto
S2a 88" SW
Tiggrr (V8 trialler)


 
On or around Fri, 11 Nov 2005 19:07:49 -0000, "Richard Brookman"
<[email protected]> enlightened us thusly:

>All the stuff about accurate to -0/+10% is C&U regs, as
>I understand, and unlikely ever to be tested in the real world.

but of course, if you arrange for it to under-read, by, for example, fitting
bigger wheels, then it's not too clever to claim "well, it only read 30 on
my speedo, officer" when nabbed.

I was thinking about this in respect of the minibus. Got a long term plan
to replace the 195R14s (which is as big as you can go on the standard rims,
original tyres are 185R14) with 205R16s, thereby making it ride better,
increasing the ground clearance and increasing the choice of tyres.

This will require, among other things, the acquisition of 7 Iveco van
wheels, which are the right size, type and stud spacing but will need
chamfers on the stud holes as they have a different type of nuts. It may
require some minor mods to the front wheel arches.

a bit of calculation yields that the original 185R14s have a nominal
diameter of 25.7", whereas 205R16 have a ND of 28.9", which will raise the
gearing by about 11%. This will not be a bad thing as the current 5th gear
is usable at any speed over about 30 mph, whereas the current 1st gear is
flat out at about 15 mph.

However, it will result in the speedo reading, for example, about 53 mph at
a real 60 mph, presuming it was accurate before. Obviously, I'll take steps
to check it, but presuming it is that far out, I was reckoning on making a
new set of figures on a bit of paper and pasting it onto the speedo dial.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Satisfying: Satisfy your inner child by eating ten tubes of Smarties
from the Little Book of Complete B***ocks by Alistair Beaton.
 
On Fri, 11 Nov 2005 20:52:31 +0000, Austin Shackles
<[email protected]> wrote:

>On or around Fri, 11 Nov 2005 19:07:49 -0000, "Richard Brookman"
><[email protected]> enlightened us thusly:
>
>>All the stuff about accurate to -0/+10% is C&U regs, as
>>I understand, and unlikely ever to be tested in the real world.
>
>but of course, if you arrange for it to under-read, by, for example, fitting
>bigger wheels, then it's not too clever to claim "well, it only read 30 on
>my speedo, officer" when nabbed.
>
>I was thinking about this in respect of the minibus. Got a long term plan
>to replace the 195R14s (which is as big as you can go on the standard rims,
>original tyres are 185R14) with 205R16s, thereby making it ride better,
>increasing the ground clearance and increasing the choice of tyres.
>
>This will require, among other things, the acquisition of 7 Iveco van
>wheels, which are the right size, type and stud spacing but will need
>chamfers on the stud holes as they have a different type of nuts. It may
>require some minor mods to the front wheel arches.
>
>a bit of calculation yields that the original 185R14s have a nominal
>diameter of 25.7", whereas 205R16 have a ND of 28.9", which will raise the
>gearing by about 11%. This will not be a bad thing as the current 5th gear
>is usable at any speed over about 30 mph, whereas the current 1st gear is
>flat out at about 15 mph.
>

Why not keep the ground clearance the same, fit 205/60R16's and the
speedo will be correct.......

Alex
 

Thanks for all the excellent helpful advice guys. Another thought
occurs, do my insurers need to know about a change in tyre size? I'm
just with the coop at the mo and I guess that as soon as I start talking
about modifications the premium will hike so I'd be best looking at a
land rover specialist insurer anyway.

Regards,

Dave.

Dave Smith wrote:
> Hi all, I have the stock 205/80R16's on my '92 D90. I would like to use
> my vehicle to a lot more greenlaning, to get to work safely in all
> winter conditions, and also to go on some of my own land. I have looked
> through the mags at tyres and it seems the BF Goodrich AT KO's are well
> recommended, so unless there's any sage advice to the contrary I've
> pretty much decided to get that make. However, what size should I get?
> My strictly non-expert instinct is wider is better for ultimate grip, so
> I've been eyeing up some 265/75R16's in one of the LRM ads. However, I
> still have several unknown questions to be answered :-
>
> a) Will 265/75R16 fit (height and width) without rubbing on my D90?
> b) Is there a good reason not to go for such a wide tyre?
> c) The tyre is 10% bigger than stock, and one (car) site recommended
> against over 2.5% bigger due to the brakes not coping. Is this true for
> a D90?
>
> Many thanks in advance for any help experiences, good advice, bad advice
> and general abuse to the obvious newbie question :)
>
> Regards,
>
> Dave.
>
 
On or around Fri, 11 Nov 2005 22:23:28 +0000, Alex
<[email protected]> enlightened us thusly:

>On Fri, 11 Nov 2005 20:52:31 +0000, Austin Shackles
><[email protected]> wrote:
>
>>On or around Fri, 11 Nov 2005 19:07:49 -0000, "Richard Brookman"
>><[email protected]> enlightened us thusly:
>>
>>>All the stuff about accurate to -0/+10% is C&U regs, as
>>>I understand, and unlikely ever to be tested in the real world.
>>
>>but of course, if you arrange for it to under-read, by, for example, fitting
>>bigger wheels, then it's not too clever to claim "well, it only read 30 on
>>my speedo, officer" when nabbed.
>>
>>I was thinking about this in respect of the minibus. Got a long term plan
>>to replace the 195R14s (which is as big as you can go on the standard rims,
>>original tyres are 185R14) with 205R16s, thereby making it ride better,
>>increasing the ground clearance and increasing the choice of tyres.
>>
>>This will require, among other things, the acquisition of 7 Iveco van
>>wheels, which are the right size, type and stud spacing but will need
>>chamfers on the stud holes as they have a different type of nuts. It may
>>require some minor mods to the front wheel arches.
>>
>>a bit of calculation yields that the original 185R14s have a nominal
>>diameter of 25.7", whereas 205R16 have a ND of 28.9", which will raise the
>>gearing by about 11%. This will not be a bad thing as the current 5th gear
>>is usable at any speed over about 30 mph, whereas the current 1st gear is
>>flat out at about 15 mph.
>>
>
>Why not keep the ground clearance the same, fit 205/60R16's and the
>speedo will be correct.......

defeats the object - I'm trying to get it to ride more smoothly on small,
sharp bumps. Fitting 195 instead of 185 section tyres has improved it. But
the series III on it's 750R16s rides more smoothly on the same bit of
terrain. Admittedly, it's on parabollocks, but then so's the minibus. from
my observation, low profile tyres add harshness to the ride. Smaller wheels
likewise, since the bumps are larger by comparison with the tyres.

There's also the issue of tyre availability - 205R16 is a very common size,
fitted to loads of things, from jap trucks to rangies to 90s to discos. The
old standard van tyres, 185R14 and 195R14 are on the decline - transits went
to 15" wheels some time ago and now to 16" wheels with 175/70 or 185/70R16
style tyres on, and other vans likewise. Bugger all point, IMHO - you don't
need the sharp handling that lower profile tyres give in a van, ferfexache.
But the effect is that "traditional" van size tyres are getting more
difficult to find and/or less choice.


--
Austin Shackles. www.ddol-las.net my opinions are just that
Too Busy: Your mind is like a motorway. Sometimes it can be jammed by
too much traffic. Avoid the jams by never using your mind on a
Bank Holiday weekend.
from the Little Book of Complete B***ocks by Alistair Beaton.
 
In message <[email protected]>, Richard Brookman
<[email protected]> writes
>...and Jon spake unto the tribes of Usenet, saying...
>
>
>> On Thu, 10 Nov 2005 16:00:07 +0000, hugh <hugh@[127.0.0.1]> wrote:
>>
>>> In message <[email protected]>,
>>> Dave Smith <[email protected]> writes
>>>>
>>>> Hi all, I have the stock 205/80R16's on my '92 D90. I would like to
>>>> use my vehicle to a lot more greenlaning, to get to work safely in
>>>> all winter conditions, and also to go on some of my own land. I
>>>> have looked through the mags at tyres and it seems the BF Goodrich
>>>> AT KO's are well recommended, so unless there's any sage advice to
>>>> the contrary I've pretty much decided to get that make. However,
>>>> what size should I get? My strictly non-expert instinct is wider is
>>>> better for ultimate grip, so I've been eyeing up some 265/75R16's
>>>> in one of the LRM ads. However, I still have several unknown
>>>> questions to be answered :-
>>>>
>>>> a) Will 265/75R16 fit (height and width) without rubbing on my D90?
>>>> b) Is there a good reason not to go for such a wide tyre?
>>>> c) The tyre is 10% bigger than stock, and one (car) site recommended
>>>> against over 2.5% bigger due to the brakes not coping. Is this true
>>>> for a D90?
>>>>
>>>> Many thanks in advance for any help experiences, good advice, bad
>>>> advice and general abuse to the obvious newbie question :)
>>>>
>>>> Regards,
>>>>
>>>> Dave.
>>>>
>>> 265/75 is standard fit on later D90s - my 98 50th Anniversary has
>>> them.
>>>
>>> You will need to reduce your lock and this will reduce your turning
>>> circle quite a bit. I certainly noticed a difference compared to my
>>> 84 D90 with 235/85 which personally I think is a better tyre for
>>> off road use.
>>>
>>> Your speedo will also be outside legal limits with the taller tyre
>>> and you will need to sort that out. I don't think you have to change
>>> the actual instrument, but no doubt someone more expert than me will
>>> be able to tell you how it's done on a 90.
>>
>> I have found that now I have the 235x85R16s on my speedo is spot on
>> when tested against the GPS. I also have the factory fit gear cog.
>>
>> If you bother to change your speedo its an easy job to do, the gauge
>> doesnt need to be changed but there is a little plastic cog that fits
>> into the Transfer Box (at the end of the speedo cable) - They are
>> colour coded so its easy to see which one you have. I think from
>> memory they are blue and yellow... or is it green? Personally I'd
>> just put the tyres on and forget about the speedo thing...But thats
>> just my opinion.
>>
>> Jon
>>
>>>
>>> I wouldn't take too much notice of what you read on car sites. It
>>> doesn't often translate onto Land Rovers.
>>>
>>> HTH
>
>I found the same going from 205s to 235/85s on a 90. No changes to the
>speedo at all.
>
>FWIW, and IA (definitely) NAL, but I don't think there is a legal
>requirement to have an accurate speedo. The law simply requires that you
>drive within the speed limit - how you arrange that is up to you. I don't
>think speedo accuracy (or even the presence of one) is an MoT test point
>either. (At least, a search on http://www.motuk.co.uk/ for "speedometer"
>gives no matches.) All the stuff about accurate to -0/+10% is C&U regs, as
>I understand, and unlikely ever to be tested in the real world.
>
AIUI your speedo must not read slow. Speaking entirely from memory, I
think you are allowed a 10% error if your speedo is fast ie indicates a
speed higher than your actual speed. Logical really.

It is an offence not to have a speedo which falls within the legal
requirements of accuracy. The fact that it is not an MOT point doesn't
mean it's not illegal.

If you increase the diameter/circumference of your tyres then your
speedo is going to read slow by the same percentage.

If you go from, say 7.50 x16 to 235/85 then they are virtually the same
diameter, but a 235/85 is quite a bit taller than 205s - which is why
the OP is considering changing in the first place, and why there are the
different drive arrangements as someone has already mentioned.

7.50s of course were standard fit on 110s and on military 90s.
--
hugh
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