craddock black modulars

Anybody got some?
I am thinking of getting some new wheels with some extra offset for the
109. I would like the normal tyres to line up with the edge of the
bodywork.
Craddocks say that they have a 'positive 8' offset but I'mnot sure what
that means

TIA
--
Mark Roberts

Hi Mark - the positive offeset means that they stick out more than the
original rims - they help to fill the wheelarches. Would look good on
the 109!

Positive 8 - 8mm?

Landylover wrote:

> Hi Mark - the positive offset means that they stick out more than the
> original rims - they help to fill the wheelarches. Would look good on
> the 109!
>
> Positive 8 - 8mm?

Positive means that the tyre centreline is inboard of the wheel mounting
face on the hub. I imagine, as you suggest, that 8 will be 8mm.

Get your existing wheel and put a straight edge across the inside
extremity of the tyre wall (the edge of the rim would do equally well
but is not so easy to reach). Measure from the face of the rim that
contacts the hub to the straight edge - distance A.

Put the straight edge across the outer extremity of the tyre wall and
measure (from the same relative side of the straight edge as used
before) through the hole in the centre of the rim to the face of the rim
that contacts the hub - distance B.

Subtract B from A and multiply by one half i.e. 0.5(A-B). This is likely
to be a postive number with the meaning defined above. For the original
Disco steel rim it's about 33mm and positive.

Assuming that your rim also gives a positive value of 33mm for the
0.5(A-B) distance, then fitting the 8mm positive rim means that the
(same) tyre on the modular rim will be 25mm (33 minus 8) further out
than it is on your existing rim.

I wanted to do an ASCII picture to explain this but couldn't get the
horizontal registration correct. Sorry.

In message <[email protected]>, Dougal
<DougalAThiskennel.free-online.co.uk@?.?.invalid> writes
>Landylover wrote:
>
>> Hi Mark - the positive offset means that they stick out more than the
>> original rims - they help to fill the wheelarches. Would look good on
>> the 109! Positive 8 - 8mm?
>
>Positive means that the tyre centreline is inboard of the wheel mounting
>face on the hub. I imagine, as you suggest, that 8 will be 8mm.
>
>Get your existing wheel and put a straight edge across the inside
>extremity of the tyre wall (the edge of the rim would do equally well
>but is not so easy to reach). Measure from the face of the rim that
>contacts the hub to the straight edge - distance A.
>
>Put the straight edge across the outer extremity of the tyre wall and
>measure (from the same relative side of the straight edge as used
>before) through the hole in the centre of the rim to the face of the
>rim that contacts the hub - distance B.
>
>Subtract B from A and multiply by one half i.e. 0.5(A-B). This is likely
>to be a postive number with the meaning defined above. For the original
>Disco steel rim it's about 33mm and positive.
>
>Assuming that your rim also gives a positive value of 33mm for the
>0.5(A-B) distance, then fitting the 8mm positive rim means that the
>(same) tyre on the modular rim will be 25mm (33 minus 8) further out
>than it is on your existing rim.
>
>I wanted to do an ASCII picture to explain this but couldn't get the
>horizontal registration correct. Sorry.

Meanwhile...
I found this:
http://www.rsracing.com/tech-wheel.html

So I think I understand it now. Just got to measure my old 109" 7.5 x
16 rims in the morning.

Thanks.

--
Mark Roberts

OK lets see if I've got this right...

Landrover tyre bulges out say 25mm from rim.
Existing rims are 65mm inboard of bodywork
tyres are 40mm inboard
I want my tyres to be flush with the body work.
So I need my new rims to be 40mm further out than the existing rims

Existing rims have 178mm rim width
Centreline is 89mm
backspace is 125mm
offset is backspace less centreline
offset is 36mm positive

so moving the tyre 40mm will reduce my positive offset and give me 4mm
negative offset.

Craddocks modulars are 8mm positive.
I assume I will be left with tyres 12mm inboard of bodywork

Did I get this right? Maybe its sensible to have them 12mm inboard

--
Mark Roberts