just got my S and noticed that my back tyres are slightly more low profile than my rears.. is this normal?

front: 255/40/18
back: 255/35/18

 

No, that is not normal or recommended. Are you sure they are 225's all around? A 255/35 is a typical rear size and proper diameter.

 

^ Unless he has rims that are all the same width, which would sorta suck because that means they are skinnier than stock.

Anyways, all the cars I have owned, the rears were slightly lower profile. The stock sizes for the ap2 wheels are 215/45/17 in the front, and 245/40/17 in the rear.

 

ah sorry that was a typo - its 255!

so its normal for the back to be slightly lower profile? why is this?

 

If you're running unstaggered widths, then yes staggered height is weird/not normal.

Normal OD for an 18 in 255 width is 255/35/18. (usually going to be ~25")

 

There was another thread just today that covers this. The number for the sidewall height is a percentage of the width, not a fixed number. If you have 225/40, 255/35 then that is near perfect. 40% of 225 is almost identical to 35% of 255. You edited your post to 255's all around, is that correct?

 

if you have 255 all around no its not normal to have 40 in the front and 35 in the rear.

your fronts are taller than your rears right now.

you can use this tire size calculator to calculator the sizes.