Maximum Tyre Size on P38 on 18" rims

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DM68

Active Member
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246
Hi everyone, pub quiz time.

I currently have a set of 255/50/19 tyres on my p38.

Now the question is can i put some 265/65/18 tyres onto it. I know your supposed to only increase your size by +/-2.5% but fitment of these tyres would increase it by 8.67%.

So has anyone fitted this size tyre and if so,is there any adverse effects or not.

Now there's no prize on offer for good answers, just a big thanks.

And before anyone points out yes i know 18" tyres wont fit on 19" rims.
 
It'll probably rub the body at access level, other than that no great problems that could't be gotten round by adjusting the height level for motorway height.
 
Cheers for the link very informative and yeah probably adjust motorway cruise height with my Faultmate.But just have to have these tyres BF Goodrich AT's they look bloody brilliant and look to fill the arches abit better in my opinion.
 
For comparative purposes I run 255/60/18 and have experienced no rubbing issues.
 
Cheers for the replies.

edc cheers for comparision but your overall wheel height is actually less than my 19's and i'm wanting to add another 65mm to overall diameter.

Rangeroverp38DSE your tyres are actually slightly bigger than my proposal but you have a 2" lift which i'm not going to do,but i bet they look the dogs b*ll*cks.

Think i'll just fit them and play around with the ride heights,just waiting for new spigots and nuts before i fit them.So thanks so far and i'll report on the outcome, cos they do look abit of a tight fit,but havihg said that they do look the part.
 
Well I have a coil converted RR and I put that tire size. It does rub the inner cover around the shock in the front and the mud flap only with the wheel turned fully and the suspension travels upward. The rear also rubs a littler in the same conditions. But it is nothing to worry. I put on a set of Hankook dynapro ATM
 
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RR3 003.jpgI told you they looked good.

Only rub ever so slightly if your on full lock and mount a kerb in standard ride height.

Access height driving a big no no but hoping to sort this out with my faultmate and the system is working fine no leaks so chances it'll get stuck in access are remote
 
Access height driving a big no no but hoping to sort this out with my faultmate and the system is working fine no leaks so chances it'll get stuck in access are remote

Your chances of getting an EAS fault and dropping to the bump stops are the same as everyone else with a P38: high! I don't mean to harangue you but if you crusing on the motorway and it drops you'd be ****ed, and the traffic police would have a field day with you!

I suppose you could try longer bump stops to avoid this situation.
 
Yeah your correct and i'm already looking into longer bump stops just incase it happens.

But bear in mind i've already replaced all the airbags,height sensors and airlines plus re-conditioned the air compressor so i've already reduced the chances of failure quiet considerably,plus the faultmate can clear most faults to get me home atleast.So all in all i'm quiet prepared for most eventualities.

Having said that if anyone knows where longer bump stops can be bought from please reply to this post,cheers
 
Hi spoke to 4x4 who advised me that General grabbers in 275/70/18's don't ride well on the tarmak and will rub on tight turns. He also mentioned that in the event of air suspension failure the RR will be stuck as tires will be resting in the wheel arches... Anybody had any experience as i think the above mentioned size would look good, filling the wheel arch.

In the end I fitted the 255/60/18 which look disappointing but they stick to the RR spec.
 
Hi everyone, pub quiz time.

I currently have a set of 255/50/19 tyres on my p38.

Now the question is can i put some 265/65/18 tyres onto it. I know your supposed to only increase your size by +/-2.5% but fitment of these tyres would increase it by 8.67%.

So has anyone fitted this size tyre and if so,is there any adverse effects or not.

Now there's no prize on offer for good answers, just a big thanks.

And before anyone points out yes i know 18" tyres wont fit on 19" rims.

The latter tyres have a larger rolling radius than the 19s. At an indicated 30 mph you would actually be doing 32.6 and at 60 mph 65.2. Depending on the year of your car, you would be getting close to illegal reference speedo readings. After i think 2001 definatly illegal to drive on the road.
 
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The latter tyres have a larger rolling radius than the 19s. At an indicated 30 mph you would actually be doing 32.6 and at 60 mph 65.2. Depending on the year of your car, you would be getting close to illegal reference speedo readings. After i think 2001 definatly illegal to drive on the road.

That may be so, but over 2 years after fitting them, I've never been done for speeding in the RR and its pasted 2 MOT's with them on, so unless i get pulled by a anal eagle eyed copper there staying on.:)
 
That may be so, but over 2 years after fitting them, I've never been done for speeding in the RR and its pasted 2 MOT's with them on, so unless i get pulled by a anal eagle eyed copper there staying on.:)

It's not your present 19s that are the problem but the 265-65-18s will be.
 
Standard wheels. 255/65/16 rolling radius. 231.82 cm. 255/55/18 RR. 231.76 cm.

19" wheel 255/50/19 RR. 231.72 cm. So little difference.

What you want to fit 265/65/18 RR. 251.86 cm. Speedo readings way out.
 
It's not your present 19s that are the problem but the 265-65-18s will be.

I started this thread over 2 years ago and knew then that the 18's had a bigger rolling radius then, i even included the percentage increase,so i already know all this. The car had 19's on and i changed them to the 18's with that tyre on them and like i said have not had a problem. So unless someone with a calibrated sat-nav or a really anal copper/mot tester drives it how would anyone know if its got an illegal speedo reading?
If you drive the car to set speed limits with this in mind i cant see what the problem is.
 
I started this thread over 2 years ago and knew then that the 18's had a bigger rolling radius then, i even included the percentage increase,so i already know all this. The car had 19's on and i changed them to the 18's with that tyre on them and like i said have not had a problem. So unless someone with a calibrated sat-nav or a really anal copper/mot tester drives it how would anyone know if its got an illegal speedo reading?
If you drive the car to set speed limits with this in mind i cant see what the problem is.

So with due respect, you gave the impression with your first post that you needed advise about fitting the 18s with the oversized tyres. If you already know all that, and have had them fitted for two years, why did you ask the question. Seems a bit silly don't you think?:confused::confused:
 
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