For the wheel experts

[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.

[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.

[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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[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.

[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.

[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.

[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.

[bigjae46]

Is the rear fender rolled or shaved at all?

[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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[9kracing]

Man I wish you could find that post.

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

[Chas3n]

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.

[Gearhead55]

do you have more pics of the track setup?

suspension un-weighted:


suspension compressed:

[bigjae46]

Thank you. I use a 10.5 square set with 265s for the track but this is my street set up.

do you have more pics of the track setup?

[Nate047]

The biggest variables that haven't been mentioned yet are your ride height and camber settings. If are running a more aggressive front negative camber setting you will need the lower offset front. I tend to lean on the aggressive side fitment-wise (which always gets a negative reaction on this forum) but I would suggest the 9.5 +22 and 10.5 +22 option, if your set on running staggered sized and have -3* or more negative camber up front. Also assuming you have rolled fenders and trimmed rear fenders.

This is a 9.5 +20 10.5 +20 set up with 275/35 square, -3.4* front and -2.5* rear camber:

Sheesh 🥹😮💨

[9kracing]

I would personally do 19x9 +30, and 19x10 +25 given the choices.

But that's me.