235 85 16 swap

So I am running on bf Goodrich 235 75 16 tires on a 300tdi disco 1 . I have been told these need to be changed as they are starting to deteriorate.

I already run a HD winch bumper. Thinking swapping to 23585 16 tires. Shouldn't have to trim front end. Aware may have to trim back. Most have said bump stops shouldn't need anything.
My land rover runs well and accelerates/pulls well... What I really want to know is I am going to ruin this... By completely gearing it up.. Or is it not really going to make much of a difference. Now I know this has probably been asked Alot. Thanks in advance.

try this to see the difference. https://www.tyresizecalculator.com/tyre-wheel-calculators/tire-size-calculator-tire-dimensions
A slight increase in gearing will give you slower acceleration, the need for more power in daily driving but slightly less revs when cruising. So it all depends what you are going to use them for.
When I have used the prog to give a calculation comparing both tyres and it gave me advice, (you scroll down).
It doesn't recommend it but then it wouldn't would it? Personally, unless you have seriously upped the performance of the engine, I wouldn't bother, the oomph from the engine isn't huge as it is, why give it yet more work to do?

I fitted 245/75/16, needed a very slight trim to the innermost lip of the rear arch but that was it. It did make a difference to its performance, you’d probably want to look at different ratios to suit and I think you’ll need to cut quite a bit assuming you do use it off tarmac.

AdamD1 said:

I fitted 245/75/16, needed a very slight trim to the innermost lip of the rear arch but that was it. It did make a difference to its performance, you’d probably want to look at different ratios to suit and I think you’ll need to cut quite a bit assuming you do use it off tarmac.

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Op is thinking of fitting larger diameter tyres, 85s instead of 75s, not wider, although admitting the 85 or 75 figure refers to the percentage of tread width so if the treadwidth is greater the rolling circumference will go up too.

Going from a little under 30" to a 32" wheel is a significant change, both to wheel clearances and gearing. It would be an expensive experiment if you are not happy with the result. Do you really need to do it?

Si Click said:

Going from a little under 30" to a 32" wheel is a significant change, both to wheel clearances and gearing. It would be an expensive experiment if you are not happy with the result. Do you really need to do it?

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So the current tires I have on I have been told are deteriorating. I have 4 general grabbers at2 sitting at home. I don't do long journeys in the land rover. At the moment it does accelerate well for what it is. Don't do any towing.

Are the grabbers old also?

AdamD1 said:

Are the grabbers old also?

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Grabbers on good nick. Not cracking or anything. Current bf Goodrich cracking

How old are they though? They may be past their best and may start to crack in use.

I may have missed it but what do you do with the car? They are alot bigger than standard, will mess up your gearing, speedo will under read, will mean you have to cut your bodywork to suit, possibly even the doors. If you’ve not got a reason to need that size I definitely wouldn’t bother. I went to 245/75 to gain a little diff clearance, it does seem to be enough for what I need/want but it did make a difference to how it drove, maybe less so to the Td5 they are now on. Fitting massive tyres just because you have them isn’t a good move in my opinion, you’ll make the car worse in every way.

It won't be worse in every way as you will improve actual ground clearance by about an inch (more if your current BFGs are really worn). But unless you actually need that extra clearance, it will make it worse in every way that matters.
OTOH if you already have the tyres standing idle, fit them and see if you like the change. You can always replace them with new at the original size and have only lost the fitting cost.

Basically what I said. And if they are old regardless of how they look now they may well be past their safe life anyway. Check for a date on them.

By a strange coincidence I went from Goodrich ATs to some road-only tyre to General grabbers. I do a lot of towing on Mways and also a bit of off road. The General Grabbers are every bit as good as the Goodrich ATs.
As for the condition of them. Provided they have been properly stored, for not too long, have no cracking in the sidewalls, (remember even the slightest cracks get a fail now at MOT, more or less) and no obvious cuts or punctures that haven't been repaired, then I really seriously would put them on. As others have more or less said, what have you got to lose? You do not say if they are already on wheels or not, but if they are then it is a no-brainer.
If not then when you take the truck to have them fitted, if you know the tyre fitter well and he is a decent bloke, he should be honest with you about the condition of them.
Just thank your lucky stars you do not live in France where any tyre over 5 years old is deemed as dead, no matter what the condition!

Also if you don't do long journeys, you'll be spending a lot of time driving around using more fuel than is necessary. If you really need the lift then that REALLY is the only reason to think of fitting taller tyres but as others have said it will mean a heck of a lot of mods to the bodywork.

Stanleysteamer said:

Also if you don't do long journeys, you'll be spending a lot of time driving around using more fuel than is necessary. If you really need the lift then that REALLY is the only reason to think of fitting taller tyres but as others have said it will mean a heck of a lot of mods to the bodywork.

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Would the lower gearing not result in lower revs at cruise speed and a fuel saving, or is this offset by using more revs to get the same acceleration at lower speed?
Surely people only need to to lift so that they can fit taller tyres? Cannot think of a single reason to lift otherwise.

Si Click said:

Would the lower gearing not result in lower revs at cruise speed and a fuel saving, or is this offset by using more revs to get the same acceleration at lower speed?
Surely people only need to to lift so that they can fit taller tyres? Cannot think of a single reason to lift otherwise.

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You are right on both counts in your first para. The first upside would not happen as he says he doesn't do long journeys, while the downside is there most of the time.
You are right about the lift too. Although it can occur accidentally, for instance if you fit heavy duty springs. The only tiny advantage I can see in that is that it would get the axle away from the bumpstops a bit for when you are carrying really heavy loads and compressing the springs a long way. For instance if you load up the back with a stere or more of hardwood timber to burn in your log burner and then have to drive down a bumpy country road to get home with it, as I have to do once every couple of years! In my D1 with heavy duty springs, I have the accidental lift and the bumpstops are never heard from. In my D2 with ordinary springs I have to be very careful! "Airbags" I know! wouldn't have the wretched things!

Sounds fair.

Jesse300tdi said:

So I am running on bf Goodrich 235 75 16 tires on a 300tdi disco 1 . I have been told these need to be changed as they are starting to deteriorate.

I already run a HD winch bumper. Thinking swapping to 23585 16 tires. Shouldn't have to trim front end. Aware may have to trim back. Most have said bump stops shouldn't need anything.
My land rover runs well and accelerates/pulls well... What I really want to know is I am going to ruin this... By completely gearing it up.. Or is it not really going to make much of a difference. Now I know this has probably been asked Alot. Thanks in advance.

Click to expand...

I run 265's with no issues at all and I tow and off road mine