[DLEFTY]

I see a popular set up as 265/35-18 fronts and 295/30-18 rears, but with such a decrease in overall diameter PLUS the rear diameter then being shorter than the front, will that mess with the stock traction control electronics? I would leave fully on or in MDM and need it all to work correctly, thoughts?
If staying staggered, what’s best for ultimate grip?

[bentom2]

Originally Posted by DLEFTY

I see a popular set up as 265/35-18 fronts and 295/30-18 rears, but with such a decrease in overall diameter PLUS the rear diameter then being shorter than the front, will that mess with the stock traction control electronics? I would leave fully on or in MDM and need it all to work correctly, thoughts?
If staying staggered, what’s best for ultimate grip?

By best ultimate grip, I assume you mean the quickest way around the track. If so, member FaRKle! did a nice test and concluded that a 20mm stagger was quickest on his car, at his local track. I’d tend to agree with him if staggered is what you prefer.

The combo you’re referring to is popular because of the A052 and another popular tires have been available in that setup, not because they’re the ideal combo for the car. If you keep the stagger at 20mm, and maintain the same aspect ratio front to rear, the DSC and TC systems will be happiest.

I’ve personally run the following and had no issues with DSC or TC;

- 245/265 40r18
- 255/275 40r18
- 265/285 35r18
- (I intend to try 275/295 35r18 soon now that there’s a tire in this combo that I’m interested in)

I’ve also run a bunch of combinations that are outside of this formula that have worked fine after a few miles- the car seems to have some ability to learn/accommodate various diameter differences front to rear after you put some miles on them. What does upset it is to bolt them on at the track and send it, when your street configuration isn’t a similar diameter difference.

[ZM2]

275 & 295/35/18 RE-71RS is where you want to be. What wheels?

[DLEFTY]

Originally Posted by bentom2

By best ultimate grip, I assume you mean the quickest way around the track. If so, member FaRKle! did a nice test and concluded that a 20mm stagger was quickest on his car, at his local track. I’d tend to agree with him if staggered is what you prefer.

The combo you’re referring to is popular because of the A052 and another popular tires have been available in that setup, not because they’re the ideal combo for the car. If you keep the stagger at 20mm, and maintain the same aspect ratio front to rear, the DSC and TC systems will be happiest.

I’ve personally run the following and had no issues with DSC or TC;

- 245/265 40r18
- 255/275 40r18
- 265/285 35r18
- (I intend to try 275/295 35r18 soon now that there’s a tire in this combo that I’m interested in)

I’ve also run a bunch of combinations that are outside of this formula that have worked fine after a few miles- the car seems to have some ability to learn/accommodate various diameter differences front to rear after you put some miles on them. What does upset it is to bolt them on at the track and send it, when your street configuration isn’t a similar diameter difference.

Correct assumption! Cornering grip, etc…..
Great info in your reply, thanks!

What width wheels did you run your set ups on? Did you have to tweak suspension at all to make them work / fit?

[DLEFTY]

Originally Posted by ZM2

275 & 295/35/18 RE-71RS is where you want to be. What wheels?

Undecided for wheels.
Any suspension tweaks/mods needed for your sizing suggestion?

[ZM2]

Originally Posted by DLEFTY

Undecided for wheels.
Any suspension tweaks/mods needed for your sizing suggestion?

I run 18x10 ET25 & 18x10.5 ET40 with the car lowered 1/2” in the front & 3/4” in the rear. -3.1F -2.1R camber.

No issues with that setup. Altho, I know the M2C has slightly less front fender liner clearance than the OG, so you might want to confirm that front fitment with the Comp guys.

[bentom2]

Originally Posted by DLEFTY

Correct assumption! Cornering grip, etc…..
Great info in your reply, thanks!

What width wheels did you run your set ups on? Did you have to tweak suspension at all to make them work / fit?

I’m running 18x9.5 ET28 front and 18x10.5 et 40 rear. For my coilovers, I also have some 7.5mm spacers up front for tire to spring perch clearance. I’m running camber plates with 3.2 degrees of camber currently, but also ran most of the sizes I listed above on stock suspension plus camber plates with 2.8 degrees of camber.

[booya_45]

For what it’s worth, I run 275/35/18 on a 9.5in wide rim (titan 7s) and a 10mm front spacer with -3.0 camber up front on TCKline DA’s. When I started driving DE events I was using sport + mode for the first two years. Didn’t notice anything different from the stock setup regarding TC going crazy or interfering more than normal.

I run with everything off for the past 3 years. Car is much more fun, responds to throttle inputs much better without TC and DSC on. Acceleration out of corners is much more noticeable. Give it a try when you’re ready.

[LBB4BSTN]

Long time lurking here, only recently posting. With regards to widths, I've not strayed from stock as I am really happy with the feel and balance of the car stock and I'm not willing to commit the funds to continued experimenting. As they say, the enemy of good is better. I've been running 513m wheels for autocross/street for several years. I've kept stock widths as I am eternally learning the car and my limits. For autocross, on the 18s I've run the Hankook RS4. The RS4 is a wide tire. No problems with TC/DSC on or off with those tires (as you would expect). The RS4's in the 245/40 and 265/40 R18 sizes have a lot of longevity but don't have the ultimate grip of a tire like the RT660's. I'm running 437m wheels (19 inch wheels) this year with the RT660's and have been greatly impressed. I wanted to get some A052's for the 513m wheels, but they seem to be eternally on backorder. Regardless of tire and wheel, I think the electronics are intrusive on the autocross course, so I'd run with them off (minus rainy days if you drive to events and don't want to end up on a curb or in a creek). From my forum browsing and talking with other M2's at SCCA events I'd try to get more camber up front before I'd go much wider on the tires. Unless you are in B Street in which case I think your only option is camber correction hubs or something like that.

[pal]

I've run the following setups on 513M wheels (18x9et29 front, 18x10et40 rear) on my 2018 M2 with KW Clubsport coilovers, a 10mm spacer up front, and -3.2° front camber.

245/265 40/18
255/275 40/18
265/285 35/18

No issues with any of these setups wrt TPMS or anything else. On track I drive with DSC Off.

On 19's (437M wheels, same width and offset as the 513M), I've run the two combos below so far. Also, without any issues.

245/265 35/19
255/275 35/19