one run-flat tire on my z a problem??

[bmarcinczyk14]

I recently had a flat tire in the rear and currently the car has a spare on the rear left. i purchased a used potenza re050a on ebay for $130 but at the time didn't realize it was a run-flat version. just received it today and noticed this. is it a safety hazard to have one run-flat tire on the rear while all the others are regular versions? the run-flat is the exact same brand as the rest if that helps any.

EDIT: just noticed on tirerack it says that re050a run-flat is for use on OE bmw vehicles only? hope that isn't another issue?

[kenchan]

i think probably okay since outer diameter should be the same.

but tire response is different between runflat and non-runflat tires so i would keep the psi on the higher end around 37-38 (cold) so that the non-runflat performs similarly to the stiffer runflat.

if you can return it, i recommend doing that and get the right one.

[bmarcinczyk14]

Originally Posted by kenchan

i think probably okay since outer diameter should be the same.

but tire response is different between runflat and non-runflat tires so i would keep the psi on the higher end around 37-38 (cold) so that the non-runflat performs similarly to the stiffer runflat.

if you can return it, i recommend doing that and get the right one.

the runflat is at 26.7" diameter while all the non runflats are at 26.5". Is that enough to worry or affect anything?

[chrischhorn]

the run flat side is going to ride like crap. no way to solve it. over inflating the other will compensate to make an even crappier ride. the RE050's dont have much sidewall flex but the car will feel different when it comes to rolling to that side compared to the other side. it wont hurt anything other then your ride quality.

[bmarcinczyk14]

Originally Posted by chrischhorn

the run flat side is going to ride like crap. no way to solve it. over inflating the other will compensate to make an even crappier ride. the RE050's dont have much sidewall flex but the car will feel different when it comes to rolling to that side compared to the other side. it wont hurt anything other then your ride quality.

will i notice any performance reductions during spirited driving or any safety hazards?

[Mike]

probably. they are two different rubber compounds so they will have different levels of grip. I wouldn't use it.

[chrischhorn]

the run flat wont have as much grip as the non. thats why the base corvettes come with run flats but the Z06 and ZR1 dont. the run flat compound arent as good performance wise. your performance will suffer as some sidewall flex helps traction to catch you no flex means itll slip if the compound cant hold it.

[kenchan]

Originally Posted by Mike

probably. they are two different rubber compounds so they will have different levels of grip. I wouldn't use it.

yah, i think so too.

i would return it if you can, or get another one. which ever would work.
i personally dont like runflat tires as they run stiff and not much give.

the diameter difference is probably not enough to cause problem, but the grip could be different enough for spirited driving.

[bmarcinczyk14]

hmmm....i'll only have these tires for one last season then im getting all new ones, so i wonder if its worth re-boxing and paying shipping to return them, then trying to find another good deal on one re050a. the tirerack guy i just talked to doesn't approve of it either. i wish they would have advertised the damn tire as a run-flat.

[DEpointfive0]

Originally Posted by kenchan

yah, i think so too.

i would return it if you can, or get another one. which ever would work.
i personally dont like runflat tires as they run stiff and not much give.

the diameter difference is probably not enough to cause problem, but the grip could be different enough for spirited driving.

I agree with this part, but I also bet the corner that has the run flat will take more of a suspension beating because the tire doesn't give.

IMO, and I am in no way a tire expert (ChrisChhorn IS,) but if you're JUST streeting it, no problem, some spirited driving, be a bit more careful, unless your spirited driving is a mountain run... Then I wouldn't experiment...

[bmarcinczyk14]

it seems to be strongly advised to not mix rft with nrft, almost to the point where it seems even a worse idea than mixing completely different brand tires? is that true?

[chrischhorn]

Originally Posted by bmarcinczyk14

it seems to be strongly advised to not mix rft with nrft, almost to the point where it seems even a worse idea than mixing completely different brand tires? is that true?

performance wise possibly. safety wise no. its safer to have the matching pattern on the same axle so the difference in the tread pattern in nasty weather conditions dont fight each other. each tread is made to push water out in a certain way. 2 different tires can counteract each other making your rear end squirrely.

[kenchan]

yah channeling water between runflat and non-runflat is probably no issue. it's the same pattern that i can tell.

but the rubber compound could be different. i think probably the same on the tread side, not in the sidewall and inside.

running different pattern on the rear axle on a RWD car is a bad idea.

RFT


regular

[bmarcinczyk14]

wow i cant believe how many rft versions of our oem tires are for sale on ebay, more than the regular! i guess they are oem for bimmers. the weird thing about it is i dont know of any bmw that uses a 275/35/19 oem?

[chrischhorn]

jaguars and ashton martins lol