Anyone running 18x9 front and 18x10 rear wheels - What tire sizes are you running

[bmw m3 s50]

For what's it's worth, BMW put 9"/10" wheels (ZCP) on e9x and they went with 245/265(40) or 255/285 (GTS). People often usize to 255/275 though that does stray from what DSC expects. And e9x expects a larger diameter rear tire where e46 dsc expects them to be basically equal so I don't know how much value there is in this comparison.

This is a good point about the GTS sizing being 255/285. Tire heights are pretty similar so it should work with the e46 DSC.

The more I think about it, I may just try this size out and report back.

[Calb]

I’m running 18x9.5 front and 18x10.5 rear with 265/35/18 and 285/35/18 rear. Had to shave the rear fenders to eliminate rubbing.

[Obioban]

Agreed but 255/40 and 285/35 would be even more grip, no?

Only if you lower the pressures.

Are you asking for street use or track use?

Keeping everything else constant, for a given tire compound, grip is determined by pressure (lower pressure = more grip).

Wider tires let you run lower pressures for a given heat level, so they can indirectly allow for more grip (and are necessary on heavier cars that heat tires more). But, for street use, heat capacity isn't something most people worry about in tires (and most people aren't optimizing their pressures for grip for street use).

Wider tires come with a bunch of trade offs- worse steering feel, tram lining, increased drag, heavier, more expensive, etc. If you don't need to increase the heat capacity (aka, for street use), wider tires are worse.

[bmw m3 s50]

Only if you lower the pressures.

Are you asking for street use or track use?

Keeping everything else constant, for a given tire compound, grip is determined by pressure (lower pressure = more grip).

Wider tires let you run lower pressures for a given heat level, so they can indirectly allow for more grip (and are necessary on heavier cars that heat tires more). But, for street use, heat capacity isn't something most people worry about in tires (and most people aren't optimizing their pressures for grip for street use).

Wider tires come with a bunch of trade offs- worse steering feel, tram lining, increased drag, heavier, more expensive, etc. If you don't need to increase the heat capacity (aka, for street use), wider tires are worse.

I remember reading this in one of your posts. Can you elaborate on this a little more? Is the lower pressure allowing for a wider contract patch via shape of the tire as it contacts the ground or is it due to the tires getting to operating temperatures quicker?


What are the optimal tire pressures for the street?

[bmw m3 s50]

I’m running 18x9.5 front and 18x10.5 rear with 265/35/18 and 285/35/18 rear. Had to shave the rear fenders to eliminate rubbing.

Those wheels look great. If I had the 9.5 in the front, then the 265 would be a no-brainer.