Square Wheel/Tire Setup on a Z4M

[kcdedric]

I'm looking into getting a set of square Apex ARC-8's in 18x9.5 et35, and I was wondering if anyone had experience running the same size (street) tires on all 4 corners. I wish we could easily fit 265/35's like the E46 M3 guys can, but I'm not sure how feasible that would be without running -3 or more negative camber (which I don't want to do). So what about 255/35/18?

Would square 255/35's interfere with the DSC system?

And no, I am not trying to run a square setup just for the "stance."

[seank]

I have 265's squared on the Arc 8's and you can run as little as 2.7 degrees of camber without sticking out. I think you would be better of with staggered set-up, rather than run 255 squared.

What will you be using the car for?

[kcdedric]

Originally Posted by seank

I have 265's squared on the Arc 8's and you can run as little as 2.7 degrees of camber without sticking out. I think you would be better of with staggered set-up, rather than run 255 squared.

What will you be using the car for?

Right now, my car is primarily used as a DD with ~2-5 track days per year and at least a few "canyon carving" trips per month.

I've been running -2.5F camber for about a year and a half now, but my rear tires wear faster. I'd love to be able to rotate them so I could even out the wear and not have to replace the tires in pairs.

[avsbmw]

I am also very interested in a square set up with arch 8s. 265/35/18. I think I am going to run pilot cup tires. I know I need camber plates.

[seank]

Originally Posted by kcdedric

Right now, my car is primarily used as a DD with ~2-5 track days per year and at least a few "canyon carving" trips per month.

I've been running -2.5F camber for about a year and a half now, but my rear tires wear faster. I'd love to be able to rotate them so I could even out the wear and not have to replace the tires in pairs.

If you are already running -2.5, the wear won't be much more than with 265's. It will rub if the car is slammed, but with stiffer sway bar or stiffer springs in the front it will not rub. I am running starspec's without issue. Different manufacturers may be slightly larger.

[kcdedric]

Originally Posted by seank

If you are already running -2.5, the wear won't be much more than with 265's. It will rub if the car is slammed, but with stiffer sway bar or stiffer springs in the front it will not rub. I am running starspec's without issue. Different manufacturers may be slightly larger.

Thanks for your input on this. What are your ride heights currently at? I'll be taking the car in next week for the alignment/corner balance so I'm glad I can still toy around with the exact figures I want. My ride height right now is set at about 13.75" all around from the center cap to the fender. My front springs may be a bit too soft to run a functional height with 265s at 400#.

Also, IIRC your car has TCK coilovers as well. Do you need a spacer up front for clearance?

[beta]

You could also go 17 9.5 et 35 all around, kinda like this.

[seank]

Originally Posted by kcdedric

Thanks for your input on this. What are your ride heights currently at? I'll be taking the car in next week for the alignment/corner balance so I'm glad I can still toy around with the exact figures I want. My ride height right now is set at about 13.75" all around from the center cap to the fender. My front springs may be a bit too soft to run a functional height with 265s at 400#.

Also, IIRC your car has TCK coilovers as well. Do you need a spacer up front for clearance?

Mine is 13.75 front and 13 rear (corner balance with a 50/50 front to rear ratio).

The star spec has a much smaller circumferance that many other tires. There is a size comparison from the blue race car that was floating around the forums for a while. He measured and weighed everything if you want to check out his build page. http://www.zpost.com/forums/showthre...t=build+thread

[Spreadsheet]

I am running a set of square Apex ARC-8's in 18x9.5 et35 with Hankook R-S3 245-40-R18 tires. Also have installed a set of Vorslag AST Coilover Kits with Camber Kits, and extras. Dropped ride about 1.5" inches. Perfect in my opinion. Not too low, wells are right on top of tires, handles great and love the look, get thumbs up from outsiders all the time.

I know that 265/35/R18s will fit (barely), but didn't want to fight the setup every day since this is a daily driver for me. Went with 245/40/R18s instead.

Now ready to add sway bars to suspension.

No retractions.

[Spreadsheet]

Looking at the ride height, both front and rear are approximately 13.375" from center of cap to lower wheel well center. I do have a 15mm spacer on rear to match width of rear to fronts. Not an issues of fronts for any means.