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

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?

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?

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?

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

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.

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.

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.

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...

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.

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
http://www.tirerack.com/images/tires...a_II_ci2_l.jpg

regular
http://www.tirerack.com/images/tires...050a_ci2_l.jpg

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?

jaguars and ashton martins lol

oh yeah. X5's and 6's use em

I've been doing this for about two years since some bastard slashed my tire and I had to scramble to find a tire so I have one rear tire RF and one non-RF

I can't notice any difference and it's probably been about 10K miles that I have been running them

What tires are they?

Same as you dude!

Well I'm in no rush to get a new tire for it so figured I mine as well get the correct tire for it, especially after reading a lot of threads strongly advising against it. The seller agreed to cover half my shipping cost to return it so I'm fine with that, plus I found the right tire on ebay for only $75 with about 45% life remaining, which is around the same amount of life as the ones currently on the car.

Good idea, you might as well since you're not desperate

Only real issue is the RF is slightly heavier, otherwise no biggie

Wow, I never knew this would turn into such a ordeal. Now it looks that not only is there a run flat version of the RE050a's, but there is also 2 different regular versions as well. One with a speed rating of "Y" and the other with a "W" speed rating. I guess the 370z's come with the "W" speed rating from the factory, which means I should make sure the used tire I buy is also a "W" speed rating? It sucks because the one I'm looking at for only $75 is the "Y" version.

Going higher speed rating is not a big deal. Going lower is the issue. Take the (Y) rated tire. you will be fine.

Ok cool. Will my Z have more swagger using one tire from a Aston Martin DB9 coupe? :icon17:

only if you change all your badges to match the car they came from ;)

(goes to ebay and searches for Aston Martin knock off badges)

:bowrofl:

And if anyone dares to question my Austin Martin badges on my 370z I'll be like, "Dude, did you not see my one rear tire came off a Austin Martin?!" "OPEN YOUR EYES!"

So when all is said and done which is a better choice, a run flat version of the same tire with the correct speed rating, or a normal version of the same tire with a higher speed rating? When you think about it the tire with the higher speed rating is going to have a different construction from the original just like the run flat will have a different construction.


EDIT: Oh and forgot to add another factor to the list of which is better. The correct tire but with substantially more tread than the rest? Out of these 3 factors, which is the best and the next best choice?

If one tire is at 9/32 tread remaining while the other is at 5/32 remaining in the rear, is there a good chance I can ruin my differential? I read you should shave it if it's off from the other tire. This buying a used tire thing is really becoming a pita, maybe I should just buy 2 brand new for the rear?

It will wear unevenly but won't affect your diff

At least you're taking the time to ask around instead of buying them and figuring it out after

Ok because I've been reading that anything over 4/32" difference in tires on the same axle can cause issues with the differential? This is mainly for the AWD folks with the STI's and Evo's though from what I understand. So no one would have any problems putting a tire that's about 3/32" off of the other tire on the same axle in the rear?