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[Patronus86]

Hello all,
I've got a question on tire size and setup. I currently have the OEM 18" light alloy double spoke wheels with RFT's

Front: 18x8.0, 225/40 R18
Rear: 18x8.5, 255/35 R18

I'm trying to upgrade to a tire size, type, setup that will be optimal for occasional track use and street driving (don't feel like spending the money on a dedicated set of tract tires/wheels). I've researched a lot of threads and articles on this and other sites but I have seen a lot of conflicting opinions.

1) Which tire size is optimal for handling/performance, especially on the track? I've heard some say 17" and I've heard others say you need to go bigger. Regardless of the diameter, I'd assume wider tires are better right?

2) Almost everyone who has modded their 335i talks about spacers between the tire/wheel and the hub. I get that it looks cool, but does that degrade performance/handling?

3) I've heard that a square setup (same width) is preferred for winter driving, is a staggered setup better for high performance in the summer time?

4) Does the wheel the tire is mounted on really factor into performance. Besides weight differences, will I notice a difference between my OEM wheel and a highly-priced aftermarket set?

5) Any recommendations on tire brand/type and setup? Again, I am focused on performance/handling as well as durability. Don't care so much about looks and ride comfort.

6) @ all the track goers: What is your solution for having good, sticky set of tires on track days? Do you keep a dedicated set of track tires and put them on before every event? Besides being expensive, don't you have to mount and rebalance the wheels/tires every time you do that? Is it feasible to use the same set for track and daily use (fyi I dont drive my car a lot during the week since I use public transport to get into work).

7) Do I need camber plates if I upgrade my tires?


Sorry for the long list. Any feedback would be greatly appreciated.

[Nanometer]

1) The M3 was raced with both 19 and 18 inch wheels. The 18 inch wheels bested the 19's in terms of performance in a track setting.

2) Wheel spacers do change the balance of the car. While they do widen the stance and stabilize the car, they also will put more stresses on the wheel bearing/bushings/control arms etc. The benefits I do not know of them personally, but I would imagine them to be small.

3) Better performance from a square setup will vary from person to person. The way the car handles will be different as the front of the car will now have a better grip biased than it did before. Better or not is your call. The car will be less likely to understeer, which, generally speaking is not as safe. As a track setting it is fantastic because you can rotate the fronts and rears =). Handling better will depend on other mods and your driving style.

4) A lighter wheel is affected in two ways, by sprung mass and unsprung mass. A wheel is counted as both, sprung and unsprung which is more specifically referred to as rotational mass and non rotational. A heavy wheel with a high inertia takes longer to accelerate to speed. A heavy wheel also adds to the "lug around" weight of the car (like adding bricks in your trunk). High performance wheels benefit from both Low Inertia, and Low Weight. They "typically" go hand in hand, but not always. Daily driver you will notice no such difference. On a track with times you would likely see a difference. You just have to ask yourself if the cost benefit is worth it. Always ask yourself, which mod will benefit me the most, and what is my current budget.

5) I run Michelin Super Sports. I think they are the best well rounded tire. They have proven themselves time and time again, which would explain why they debuted on the Ferrari 458 a couple years back. There are better track options, aka non road legal options.

6) I am not a big track goer, but a lot of serious track guys have their own set of slick tires. They do not typically rebalance the wheels after every weekend, the way I see the locals drive, I wouldn't imagine them lasting much longer than one weekend anyway =-p. Again, I like the Super Sports because they are such a great all around tire.

7) Camber plates is not a requirement for just changing to a better tire. Again, I am not a weathered track goer, so maybe someone else will know more.

[jadnashuanh]

A wider tire is lousy in snow conditions and lower profile tires are much more prone to cracking a rim on the inevitable potholes hidden in the slush. So, wider, larger wheels is not a great situation for that. At the track, a wider tire has the potential of greater grip, but if you stick with RFT, the biggest benefit of lower profile tires is somewhat lost...a lower profile tire in a 'normal' version, has less squirm, but a RFT is considerably stiffer, so the difference isn't as dramatic.

Since winter driving and track use are quite a bit different, you may not find a good compromise that can do both jobs well.

Moving the wheel further out changes the track, puts a bigger load on the bearings, and may cause it to extend beyond the fender well. This is both potentially dangerous (throws stones at the guy behind you) and is illegal most places. The tire can also then hit the fender, and create big problems. You can bend the fenders to account for a tire that is wider or moved out.

For aftermarket wheels, they may need either or both of a spacer to get the wheel's offset in the proper position for clearance and centering, and maybe a centering ring so it sits perfectly on the center hub. Because the aftermarket wheel manufacturers try to get a wheel to fit as many vehicles as possible, they came up with the centering ring and spacers. The last big thing, obviously, is the number and spacing of the studs or bolts that hold the thing on, but the configuration BMW uses is relatively common but the offsets may not be.

Also, keep in mind that not all wheels will accept the TPMS sensor, which you'll probably want to keep, whatever wheels you install.

[Patronus86]

Thanks for the responses. So just to clarify,

A staggered wheel setup is preferred for summer time performance?

Which tire size is better (performance wise) for the 335i? 17" or 18"?

If I plan on tracking/hard driving, I should forgo the wheel spacers? Unless of course I get an aftermarket wheel that requires it. But in general, wheel spacers aren't good for your control arms, wheel bearings, bushings, ect?