Another Don

It's about time to replace the tires on my Targa. Current tires are a weird mixture of Continentals/front and BF Goodrich/rear and frankly, I'll be glad to see them gone...

I know there are 3,759 threads about replacement tires for a narrow body, so I'm not trying to reinvent that wheel. My question concerns how to get a set of Run Flats on the car. As near as I can tell nobody makes a set of run flats in 996 OEM sizes.

But...I've found that Michelin does make the Pilot Sport PS2 ZP in the OEM size (225/40-18) for the front, so I should be halfway home. But for the rear the closest size available in this tire is a 285/30-19. So it would seem that I would have to replace the rear rims to make these work since my current rims are 18. Unfortunately, being just a little OCD, I could never tolerate having different rims on the front and the back, so I would, no doubt, be buying 4 rims.

So at this point my imagined configuration would be these Michelins on 18" rims on the front and on 19" rims on the rear. Based on my research this 19" tire is about .6" larger diameter than an OEM Pirelli Russo.

Do you think that having these differing sized rims and ever so slightly larger diameter tires (on the rear) would give my PASM computer any problems? Or cause any negative repercussions with the Active Handling?

On the plus side is that my truck would effectively double in size when I take the spare tire out and set it in my garage. On the negative side is that by the time I get 4 new rims and 4 new tires I'm probably $5k into this project compared to the $1,500 I would be out for merely replacing the 4 tires.

Now here is the obligatory pic of said car with old rims and tires...



And a pic of the most emphatic stop sign on the planet...

Barn996

Aren't run flats much heavier, and the ride quality is diminished? That's what the articles I've read suggest.

quickxotica

+1

Check out the BMW forums (like Bimmerfest) and you'll find 1,000's of posts from owners who hate their run-flats (RFTs). I'd stick with your spare and just get 4 fresh tires.

BTW: your car may have PSM, but it does not have PASM (which debut'd on the 997 cars)

Good luck with your tire quest.

Dennis C

I don't like the idea of mixing rim sizes. I'd stay away from that. I've heard the same as the other about the run-flats. You can always buy an aftermarket tire pressure monitoring system if you're concerned about flats...

buzztt

i frequent m3forum and a few other bimmer forums and have never read a post from someone who liked runflats

i'm sure they are great for peace of mind if you are a house wife driving a mini van but personally i would steer clear of them

LVDell

Problems with that choice:
1. Weight
2. Wrong Application
3. Car won't perform well
4. Not N spec tire
5. etc

Marlon

probably a learned holdover from the 'vette - they come with runflats I think.

Another Don

Yeah, the Vette does come with run flats. I trashed the OEM Goodyear RFs in favor of some Firestone Firehawk RFs and they're not a bad tire. Fairly grippy, and not a bad ride in the car. And, yes, the Vette has 19's in the rear and 18s up front.

The heavier part doesn't really bother me. Eventhough I understand the ramifications of unsprung weight, I'm not likely to track my car. It's DD duty and an occasional road trip for its primary (only?) uses.

In the end I'll probably just buy a set of tires and leave the rims alone. Sometimes when it looks too hard it probably is and not likely worth the effort...or so it seems to me.

Dennis C

I didn't realize the 'Vette had 19s in back and 18s in front. Is this the OEM set up? Still worries me a bit on a 996, but that's just my opinion.

Another Don

Yep, Corvette C6 OEM wheels are 18x8.5 front and 19x10 on the rear, except the Z06s and ZR1s that are 19x12 on the rear. The base C6s and Z06s get Goodyears from the factory and the Zr1s use that Michelin PS2 ZP as the OEM tire.

I know that's more than you ever wanted to know about Vettes, but I can't help it.

ivangene

I am not trying to be mean - but dont try and turn the Pcar into a Vette -

Tim already added side pipes and it didnt look good IMO

Jon996

Interesting idea. I like the corvette look too, but there is one other difference, I think. When the corvette goes to 19/18 for the Z06 I am pretty sure (via calculator over on 1010tires.com) that the overall diameter of the rear tire is larger than the front. I assume the electronics are calibrated for this. With the P-car I would think we need to keep the front and rear overall tire diameters the same.

SH || NC

I wouldn't; can't see the benefit vs. the risks. Also, why would you want to run run flats, besides the obvious reason of course?