For the wheel experts

[Chas3n]

Man I wish you could find that post.

FWIW the Dinan wheels I have are 19x9.5 +48, and 19x10 +35

There's many posts I wish I could find! The early 2000's were a small treasure of posts from guys like Steve and other shop/race builders sharing knowledge.

DINAN did make the whees in a variety of sizes, my previous set was 9.5 et30 (I believe?) and 10 +25


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[bigjae46]

Is the rear fender rolled or shaved at all?

[bigjae46]

There is now a long lost thread/post (believe it was on the roadfly forum) with Steve Dinan mentionion the ideal offsets for a stock control arm/bushing geometry E46 M3.

The closet setup Apex offers ( and its very close ) is 18x9.5 ET35 and 18x10 ET25

My current ARC8 set is this setup, and my pre-ordered ML10's are as well. If that post he described why wider isn't always better and why the 9.5/10 is ideal for the stock geometry suspension.

There's so much data that shows a wider front wheel/tire is outright faster in terms of lap times in most cases. There is probably a downside like tire wear, steering feel, aero drag, or bump steer. Maybe it is possible that wider front tire is slower in certain situations like a slower or tighter track or auto-x.

At my local track, a 275 is an easy 1/2 second faster than a 245.

[Gearhead55]

There's so much data that shows a wider front wheel/tire is outright faster in terms of lap times in most cases. There is probably a downside like tire wear, steering feel, aero drag, or bump steer. Maybe it is possible that wider front tire is slower in certain situations like a slower or tighter track or auto-x.

At my local track, a 275 is an easy 1/2 second faster than a 245.

The big downsides are basically tramlining and bump steer issues, I think. I think the increased scrub radius increases steering effort a little, which doesn't bother me. But for me the benefit of the wider tire far outweighs any negatives it introduces. Plus I think it looks cool. These cars should be running a 265 or 275 IMO.

My rear fenders are shaved and sealed.

[liam821]

The big downsides are basically tramlining and bump steer issues, I think. I think the increased scrub radius increases steering effort a little, which doesn't bother me. But for me the benefit of the wider tire far outweighs any negatives it introduces. Plus I think it looks cool. These cars should be running a 265 or 275 IMO.

My rear fenders are shaved and sealed.

I run 265 square on my M3 and it does tramline. I gotta say jumping into my stockish 330i with a zhp rack but a stock wheel/tire setup it's so much easier to drive. While I love the grip and performance of the wide setup on the M3, sometimes you just want to drive to the grocery store.

[nextlvel]

I run 265 square on my M3 and it does tramline. I gotta say jumping into my stockish 330i with a zhp rack but a stock wheel/tire setup it's so much easier to drive. While I love the grip and performance of the wide setup on the M3, sometimes you just want to drive to the grocery store.

As someone in the exact same situation (i have a zhp as a DD) the steering difference is crazy. I've ran the same tires on both my M3 and zhp and the zhp seems so much easier but less precise but also a little heavier. I think due to the yellow tag rack.

[Chas3n]

There's so much data that shows a wider front wheel/tire is outright faster in terms of lap times in most cases. There is probably a downside like tire wear, steering feel, aero drag, or bump steer. Maybe it is possible that wider front tire is slower in certain situations like a slower or tighter track or auto-x.

At my local track, a 275 is an easy 1/2 second faster than a 245.

I didn't mention a 245 up front was ideal.

The sizing I supplied would imply a 265 front and 275 rear setup for a street tire, and a 255 front 265 rear for a 200 or less tread wear tire (competition)

There is without a doubt, a difference in the setup of a balanced street car, and a dedicated track car. Both in the suspension setup, and possibly the geometry of the suspension if you're doing it, right.


Edit: regarding the posts about the zhp/tramlining, I don’t drive my m3 enough on commuter roads to notice how bad it tramlines, but I’m sure it’s somewhat there (although much less than a true square setup) I don’t know how to compare the steering, as my zhp is on the stock wheel/tire setup and I feel is only barely quicker than my ZCP m3/rack. If I can hunt down a wheel setup that gives the zhp a 245 - 255 tire setup this winter I’m going to go that route and see how it then compares to the M3. Should be a closer comparison at that point.

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[Bry5on]

Man I wish you could find that post.

FWIW the Dinan wheels I have are 19x9.5 +45, and 19x10 +35

Offsets like this are the way. Scrub radius will absolutely affect ability to hold ultimate grip as you chase around the limits of your tire’s grip circle instead of holding it steady. Most people run coilovers with perches below the tire, which severely hinders the ability to run a proper offset for no good reason.

I modeled my ‘stock’ M3 suspension in CAD for the fun of it. I run 17x9 et46, and if I had the fenders I’d run 18x9.5 et43 or so.

OP, you’re better served to follow the advice of folks here, keep your front offset numbers higher and the rear 25-30 range if you’re trying to maximize feel and performance. If you’re looking to make it look full, drop those offsets by 5-10mm. That’s pretty much all there is to it.

[bigjae46]

I didn't mention a 245 up front was ideal.

The sizing I supplied would imply a 265 front and 275 rear setup for a street tire, and a 255 front 265 rear for a 200 or less tread wear tire (competition)

There is without a doubt, a difference in the setup of a balanced street car, and a dedicated track car. Both in the suspension setup, and possibly the geometry of the suspension if you're doing it, right.

I picked 245 because it was my last data point that wasn't 275.

Agreed, two different situations. I appreciate the info so that I can make an informed decision.

[BigRussia]

While looking into my HPDE car’s possible bumpsteer under hard braking issue, I’ve also been suspecting my wide track wheel setup’s high positive scrub radius is contributing to me fighting the wheel and instability under hard braking. Inspired by Gearhead55, BBBRTuning here and Japanese tuners’ time attack M3s over in Japan I’ve been running a 18x10.5 et22 on 265/35 square setup since last January. I like the setup and have no fitment or rubbing issues on track, can even turn full lock with minimal fender liner rub. The front strut spring perches are maxed out on the threaded damper body, and even still the tire isn't fully under them (6” spring), there’s just a fingers width of clearance (~10mm) between the tire sidewall to the spring perch and the wheel inner lip to the damper strut body (thankfully the 265 stretched has the sidewall curving away).

So I’m considering going back down to a 10” wide wheel and wanted to see whats the highest offset i could run to bring the scrub radius down as much as possible. I test fit the 513M rear wheel from the daily (18x10 et40) with a 5mm spacer for effective et35 and was just barely able to clear the maxed out spring perch and strut body, but with a 275/35 tire. Figured I’d share my findings here as while i was researching this topic across 3 different threads on here this one had the most recent post.

Im really leaning towards picking up a new set of 18x10 ET33 wheels (both BimmerWorld and Apex have models in this spec), sticking with 265/35 tires, and running 12mm rear spacer for effective ET21. Just I have too many wheels as it is and wanted to see if it’s worth going down this route before spending money on new wheels and another set of 200tw tires.

Pics: current 10.5 et22 265/35 setup (sharpie sitting in the gap)

513M rear 18x10 et40 -5mm spacer w/ 275/35

[bigjae46]

While looking into my HPDE car’s possible bumpsteer under hard braking issue, I’ve also been suspecting my wide track wheel setup’s high positive scrub radius is contributing to me fighting the wheel and instability under hard braking. Inspired by Gearhead55, BBBRTuning here and Japanese tuners’ time attack M3s over in Japan I’ve been running a 18x10.5 et22 on 265/35 square setup since last January. I like the setup and have no fitment or rubbing issues on track, can even turn full lock with minimal fender liner rub. The front strut spring perches are maxed out on the threaded damper body, and even still the tire isn't fully under them (6” spring), there’s just a fingers width of clearance (~10mm) between the tire sidewall to the spring perch and the wheel inner lip to the damper strut body (thankfully the 265 stretched has the sidewall curving away).

So I’m considering going back down to a 10” wide wheel and wanted to see whats the highest offset i could run to bring the scrub radius down as much as possible. I test fit the 513M rear wheel from the daily (18x10 et40) with a 5mm spacer for effective et35 and was just barely able to clear the maxed out spring perch and strut body, but with a 275/35 tire. Figured I’d share my findings here as while i was researching this topic across 3 different threads on here this one had the most recent post.

Im really leaning towards picking up a new set of 18x10 ET33 wheels (both BimmerWorld and Apex have models in this spec), sticking with 265/35 tires, and running 12mm rear spacer for effective ET21. Just I have too many wheels as it is and wanted to see if it’s worth going down this route before spending money on new wheels and another set of 200tw tires.

I run 17x10 et25, never noticed any instability or bump steer under braking. Are your control arm ball joints and bushings in good shape?

[BigRussia]

I run 17x10 et25, never noticed any instability or bump steer under braking. Are your control arm ball joints and bushings in good shape?

Yeah that’s whats perplexing me, everything's pretty fresh and been replaced recently. I had new LCA installed with new wheel bearings maybe less than 2 years ago. I installed new Powerflex FCAB about a year ago. Steering rack was fully rebuilt by a local reputable shop a few years ago too, and I installed a delrin steering coupler with it. Can’t think of what it could be if suspension or bushing related :/

[Bry5on]

Yeah that’s whats perplexing me, everything's pretty fresh and been replaced recently. I had new LCA installed with new wheel bearings maybe less than 2 years ago. I installed new Powerflex FCAB about a year ago. Steering rack was fully rebuilt by a local reputable shop a few years ago too, and I installed a delrin steering coupler with it. Can’t think of what it could be if suspension or bushing related :/

It’s the power flex bushings. Terrible.

[bigjae46]

Yeah that’s whats perplexing me, everything's pretty fresh and been replaced recently. I had new LCA installed with new wheel bearings maybe less than 2 years ago. I installed new Powerflex FCAB about a year ago. Steering rack was fully rebuilt by a local reputable shop a few years ago too, and I installed a delrin steering coupler with it. Can’t think of what it could be if suspension or bushing related :/

The rear also has an effect on braking. Could be an alignment issue.

And braking technique can also cause issues. Often times I see newer drivers hammer the brakes which unloads the rear end and can cause understeer then quickly
turns into oversteer.

It needs to be an aggressive squeeze. Your job as a driver is to manage weight transfer.

[BigRussia]

It’s the power flex bushings. Terrible.

Yeah I've avoided PF products in the past since I’ve heard plenty stories online of their FCAB disintegrating. I had Turner solid monoball FCAB before but they started melting and developed a noticeable play and slop in the front end. I got these new Powerflex FCAB because they are the offset caster ones, only the small inner sleeve is poly and goes into a solid aluminum outer so I figure should hold up to the heat better. I did get an increase in caster from them verified by the alignment after the install.

The rear also has an effect on braking. Could be an alignment issue.

And braking technique can also cause issues. Often times I see newer drivers hammer the brakes which unloads the rear end and can cause understeer then quickly
turns into oversteer.

It needs to be an aggressive squeeze. Your job as a driver is to manage weight transfer.

Yeah i havent ruled out that it could be the driver being the problem lol, and that i need to work on my braking technique more. I may be smashing the brake too quickly too hard n trying to get to threshold; and maybe that’s upsetting the car and the sudden weight transfer. Im sure doesn't help either that most of the weight reduction on my car has been in the rear (also running no rsb).
Next time out I need to make it a point to try smoother braking maybe a bit earlier n see if that helps, rather than waiting for the latest possible time to brake. For pads I'm running PFC08 front and PFC11 rear (11 to get a bit more rear bias), on Renault Megane front n 996 rear retrofitted Brembos (poor mans BBK)

Rear alignment should be slight toe-in from last time, maybe just 2 track days ago unless it got out of wack since then.