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[TwinTurboed]

I have a completely stock M-Sport 135i and would like to go to a square setup. Would I be able to run 245/35/18s on all four corners? I have the 261 M wheels. I know that size works just fine on the rears as they are 18*8.5, but wondering about the fronts as they are 18*7.5.

I have searched through several threads, but did not find a good answer. Please help! Thanks!

[11135i]

Something that I've crawled through the forums for as well and it seems that most people are either running with 3mm or 10mm spacers (+other doodads)...

http://www.1addicts.com/forums/showthread.php?t=911503
http://www.bimmerpost.com/forums/sho...d.php?t=951830

It's been said that we have no room to play with in the front...

[TwinTurboed]

I just want to know if I can run 235/35/18 upfront. I know I can run 245/35/18 in the back. I think that would help dial out the understeer a bit as its close to a square setup.

[Nitrous Garage]

Stick to the 235/35/18 all around. A 245 in the front will cause trouble with rubbing either on the strut or fender.

[TwinTurboed]

Originally Posted by Nitrous Garage

Stick to the 235/35/18 all around. A 245 in the front will cause trouble with rubbing either on the strut or fender.

Wouldn't I have issues with traction by downsizing to a 235/35/18 on the rear?

[Nitrous Garage]

Originally Posted by TwinTurboed

Wouldn't I have issues with traction by downsizing to a 235/35/18 on the rear?

Oh I thought you wanted to run a square tire setup. If you want a staggered setup on stock wheels go with a 225/40 and 255/35. If you want to run spacers you can go 235/40 and 265/35.

[TwinTurboed]

Originally Posted by Nitrous Garage

Oh I thought you wanted to run a square tire setup. If you want a staggered setup on stock wheels go with a 225/40 and 255/35. If you want to run spacers you can go 235/40 and 265/35.

I want to run as close to square as possible with a stock car/wheels. I am running 225/40 and 255/35 at the moment, but was wondering if 235/35 and 245/35 would be a good setup as its close to square.

[Nitrous Garage]

Originally Posted by TwinTurboed

I want to run as close to square as possible with a stock car/wheels. I am running 225/40 and 255/35 at the moment, but was wondering if 235/35 and 245/35 would be a good setup as its close to square.

That will work but you might have to run a spacer in the front depending on the tire brand you go with. Is there a reason you want to step down the rear size and up in the front?

[TwinTurboed]

Originally Posted by Nitrous Garage

That will work but you might have to run a spacer in the front depending on the tire brand you go with. Is there a reason you want to step down the rear size and up in the front?

I want to get it as close to a square setup as possible, without purchasing new wheels, I guess to reduce understeer.

[135iam]

I run 225/40/18 snows on my stock wheels for winter driving. I agree with the other post about not going over 235 s on stock wheels, the sidewall bulge would be huge with a 245 and the steering numbness would significantly increase (the reason I would never do it)

[TwinTurboed]

Originally Posted by 135iam

I run 225/40/18 snows on my stock wheels for winter driving. I agree with the other post about not going over 235 s on stock wheels, the sidewall bulge would be huge with a 245 and the steering numbness would significantly increase (the reason I would never do it)

Would I go with 235/40/18 or 235/35/18?

[135iam]

Originally Posted by TwinTurboed

Would I go with 235/40/18 or 235/35/18?

235/40/18 is a very common size, 235/35/18 isnt. for that reason I would go with 235/40/18 (assuming you stay at stock ride height)

[TwinTurboed]

Originally Posted by 135iam

235/40/18 is a very common size, 235/35/18 isnt. for that reason I would go with 235/40/18 (assuming you stay at stock ride height)

Thanks for the help!

[keithbickford]

In theory, you have a few options. Huge tires all around will grip like mad and never understeer or oversteer. This is only a theory and does not apply. They would not fit and the weight would kill all other aspects of performance. Our cars have understeer as well as a challenge of achieving optimal traction in the rear during hard acceleration. That said, I think the BMW engineers did a great job of dialing it for us. They are automotive engineers, and I am a radio engineer. I will let them design cars, and I will design high tech gadgets. Nonetheless, I feel your frustration. So, its a matter of compromise (one word to describe all decisions made in engineering). Do you want the tail of the car to break loose before the front (oversteer)? Then go a touch wider in the front and perhaps a touch narrower in the rear. What? You don't want to lose straight line acceleration? Well, you can't have both. You must accept a compromise. It's sort of a law. That said, I like the idea of running a 225/245 combo. I run a 225/255 combo, but I think the 225/245 combo would be ideal on the track.

[TwinTurboed]

Originally Posted by keithbickford

In theory, you have a few options. Huge tires all around will grip like mad and never understeer or oversteer. This is only a theory and does not apply. They would not fit and the weight would kill all other aspects of performance. Our cars have understeer as well as a challenge of achieving optimal traction in the rear during hard acceleration. That said, I think the BMW engineers did a great job of dialing it for us. They are automotive engineers, and I am a radio engineer. I will let them design cars, and I will design high tech gadgets. Nonetheless, I feel your frustration. So, its a matter of compromise (one word to describe all decisions made in engineering). Do you want the tail of the car to break loose before the front (oversteer)? Then go a touch wider in the front and perhaps a touch narrower in the rear. What? You don't want to lose straight line acceleration? Well, you can't have both. You must accept a compromise. It's sort of a law. That said, I like the idea of running a 225/245 combo. I run a 225/255 combo, but I think the 225/245 combo would be ideal on the track.

Completely agree with you. Wouldn't a 235/245 be a better setup as it will help rotate the car more?

[keithbickford]

"Completely agree with you. Wouldn't a 235/245 be a better setup as it will help rotate the car more?"
That could definitely be true. Which ratio would cause the rear to be just slightly more loose than the front? Is it square? Were the engineers that far off? There is only one way to find out. Well, I suppose a physicist/engineer could calculate the forces and tractions under those forces. But since I'm not that guy...

[Dafttt]

In my opinion, it might look a little lopsided. If you go for a 235/40/18 tire on a 7.5" wheel, it might look questionably meaty over the opposing 245/35/18, 8.5" rear wheel.

I don't know if this helps, but here's a 225/40/18F, 245/35/18R combination I used to have on a square 8.5" wheel. Now imagine the front taller, and with a little more bulge. Just a thought.

[NickDHdfc]

i just purchased my 135. It came with a squared set up running 245/35/18 on the 8.5 inch 264 wheels. Front fenders are rolled flat and the rears seem to have a slight roll.

[JimD]

Remember that tires are not your only variable. Negative camber will increase front grip too. Tire pressure also makes a difference.

[135iam]

Originally Posted by NickDHdfc

i just purchased my 135. It came with a squared set up running 245/35/18 on the 8.5 inch 264 wheels. Front fenders are rolled flat and the rears seem to have a slight roll.

Nice! I wanted to do that but couldnt find a cheap pair of rear wheels so I bought aftermarket wheels for summer and used the 264's for snow tires.

[Bama335]

Originally Posted by NickDHdfc

i just purchased my 135. It came with a squared set up running 245/35/18 on the 8.5 inch 264 wheels. Front fenders are rolled flat and the rears seem to have a slight roll.

Any suspension mods to go along with the square 245?

Spacers?

I tried mounting the stock rear with 245/35 up front and it rubbed the strut unless I used a 5 mm and 3 mm spacer together (I didn't drive on it that way, only a fit test). I also tried a 12mm, it cleared the strut but it would need some camber plates and a fender pull.

[NickDHdfc]

No there were no spacers on the car, all stock oem suspension. I dont understand how it wasnt rubbing against the strut but it all seemed fine. I recently changed to 225/40 and 255/35 in the rear.