Anyone try a square 18x9.5 with a 275/35 for track/autocross

[ineedae46m3]

I know 18x10 ET25 seems to be the go to for the limited people running the the square setup on the F80.

Wondering if you went with the 18x9.5 which offsets would work with an Extreme Performance 275/35R18 Tire? Also if anyone has this installed how flush do they sit?

Thanks

[CanAutM3]

18X9.5 is too narrow fow optimal track performance.

[Pic18]

Originally Posted by CanAutM3

18X9.5 is too narrow fow optimal track performance.

Are you basing that solely on the tire size (275 width)? Or is there something else I am missing in that statement?

[ineedae46m3]

Originally Posted by Pic18

Are you basing that solely on the tire size (275 width)? Or is there something else I am missing in that statement?

Assuming he is basing it on tire width for the rear from his experience. Rim width shouldn’t make a difference as a 275/35 fits fine in a 9.5” wheel I think.

[CanAutM3]

Originally Posted by Pic18

Are you basing that solely on the tire size (275 width)? Or is there something else I am missing in that statement?

Just in general. A 9.5” wide wheel will not be able to extract the maximum performance from 275 tire. A 275 tire is the bare minimum that should be used at the rear for track duty and is not really sufficient to extract the performance of the engine and chassis.

[MaynardZed]

9.5" square wheels work great (with 255 tires) on my 240 hp E36 race car weighing in at 2600lbs.

I used 9.5" wide wheels on the M4 once for a drifting event, was fine for that.

[ineedae46m3]

Originally Posted by MaynardZed

9.5" square wheels work great (with 255 tires) on my 240 hp E36 race car weighing in at 2600lbs.

I used 9.5" wide wheels on the M4 once for a drifting event, was fine for that.

I mean numerous people run 275/35R18 NT01 tires on 9.5” Apex wheels on the fronts of their F8X cars for track use. I guess what would the difference in the the rear be.

Lots of M2 guys are running 18x9.5” square setups with 275/35 on the Tire Rack Rims. I understand the power from the N55 is different than a S55, etc.

[MaynardZed]

Originally Posted by ineedae46m3

I mean numerous people run 275/35R18 NT01 tires on 9.5” Apex wheels on the fronts of their F8X cars for track use. I guess what would the difference in the the rear be.

Lots of M2 guys are running 18x9.5” square setups with 275/35 on the Tire Rack Rims. I understand the power from the N55 is different than a S55, etc.

Difference is just getting the power and torque down from the S55. You're not wrong to run the 275 square setup if you really want to, especially for autocross. Should be good car control practice, but you're gonna give the steering wheel a workout. Nothing wrong with that for sure.

[CanAutM3]

Originally Posted by ineedae46m3

I mean numerous people run 275/35R18 NT01 tires on 9.5” Apex wheels on the fronts of their F8X cars for track use. I guess what would the difference in the the rear be.

Lots of M2 guys are running 18x9.5” square setups with 275/35 on the Tire Rack Rims. I understand the power from the N55 is different than a S55, etc.

The M3/4 are significantly under tired from the factory. Particularly at the rear. However, when putting more rubber in the rear, the front also needs to be increased to keep the handling in balance. The stock rear wheel is 10”. I would not go for anything narrower as it will make the rear wobbly due to sidewalk deflection. Then the question that begs to be asked is why run a 9.5” wide square setup when one can easily run a more optimal 10” wide square setup?

[ineedae46m3]

Originally Posted by CanAutM3

The M3/4 are significantly under tired from the factory. Particularly at the rear. However, when putting more rubber in the rear, the front also needs to be increased to keep the handling in balance. The stock rear wheel is 10”. I would not go for anything narrower as it will make the rear wobbly due to sidewalk deflection. Then the question that begs to be asked is why run a 9.5” wide square setup when one can easily run a more optimal 10” wide square setup?

Simply due to cost of some 18x9.5” wheels available. I appreciate the explanations though, I am just trying to look at all the options available to me.

[CanAutM3]

Originally Posted by ineedae46m3

Simply due to cost of some 18x9.5” wheels available. I appreciate the explanations though, I am just trying to look at all the options available to me.

For a few hundrad dollar difference, just go with the 10".

Or even better, a 10"-11" staggered setup