New Z4M owner. Couple questions about tires!

[NickC]

Hi guys,

I'm a long time bimmer owner, having owned an E36 M3, two Z3 M roadies, an S54 M coupe, an E46 M3, and most recently an 02 M5. I took a nearly three year hiatus from bimmers while I drove my 05 Pontiac GTO (it's an outstanding car and an M5 for less than half the cost), but now I'm back with an ///M roadster.

I just had a quick question about tires. I know on my old ///M roadie, you could damn near throw any tire size on the rear. Coming from my 05 GTO, I'm a bit more tuned into the wonderful joy of rubbing.
I notice the stock tires are 225/45/18, and 255/40/18. Is it totally possible to throw a 245/40/18 on front and a 275/35/18 on the rear without any sort of rubbing or other modifications needed? Thanks!!

[iranmeba]

I've been doing quite a bit of research on this topic myself lately and have come to this conclusion, please anybody correct me if i'm wrong.

245 should be fine in the front but squeezing one onto an 8 inch wide rim is not recommended. You should have at least an 8.5 inch wheel if you want tires that wide.

For the rear, again 275 should be fine but you'd want at least a 9 wide wheel.

I'm picking up a set of CSL reps really soon and those are the tire sizes I'm probably going to get.

[NickC]

I've been doing quite a bit of research on this topic myself lately and have come to this conclusion, please anybody correct me if i'm wrong.

245 should be fine in the front but squeezing one onto an 8 inch wide rim is not recommended. You should have at least an 8.5 inch wheel if you want tires that wide.

For the rear, again 275 should be fine but you'd want at least a 9 wide wheel.

I'm picking up a set of CSL reps really soon and those are the tire sizes I'm probably going to get.

Hi, thanks very much for the reply! Aren't the stock ///M rears 18x9? I'd be good there. As well, my GTO had 235/40/18s on an 18x8 wheel (stock), so I know a 245 would fit just fine.

Has anyone run a 245 on the front, stock ///M wheels? Thanks!

[dtothepowerofp]

Absolutely. I ran this size tire on my stock wheels and had no issues with rubbing. They were Toyo RA-1's which I believe are sized a little larger than is stated. This was track use (2 wheel curb hopping/full G Loads) so you won't have any problem on the street either. Lowering the car won't cause this size wheel/tire to rub either.

[schwank]

I did a small writeup on some dunlops over on bimmerfest.
http://www.bimmerfest.com/forums/sho...d.php?t=294185

Z4 mc 245/40/18 & 275/35/18 Dunlop direzza sport z1 star spec
For anyone who wanted to know if you can fit this size tire on STOCK z4m rims, they work great. No rubbing, no problems, reset the tire sensor and everything has been perfect. I do notice the car seems to want to track straight more, and is SLIGHTLY heavier to turn but it isn’t noticeable after a few days.

I don’t have a lot of experience with ultra high performance super sticky tires however these things are great! They heated up quickly at the track, and never over heated. I ran eight 25 minute track sessions in two days. My first session out I hadn’t let enough air out of them and the pressures spiked at about 45psi leaving me sliding around the track (Id suggest starting at about 32psi cold temp). The Dunlops gave me a nice audible howl when pushed to the limit, and performed consistently.

I read that these like to “chunk” when they are used new on the track, I drove about 600 miles on them before tracking them and had no problems. I drove through a good sized downpour before the track and was very happy with he wet traction. Litteraly leaving the track it started raining HARD and at highway speeds the car was rock solid on these tires even after a good heat cycle. I have not had to deal with much standing water, and these are not designed to.

Overall I would buy these tires again for street and track use. I would say one weekend at the track used about 50% of the tread depth (evenly for the most part) and they are louder after the track event at highway speeds.

[NickC]

Thanks for the replies guys, I really appreciate it! This will definitely be the setup I go with soon. Thanks!