dudeasca

hey there
i must change the tires , especially in the rear cause they have no “meat”
i have the stock amg 18inch wheels
255 35 rear
and 235 40 front

was thinking to make my car more confortable , cause we have big potholes here in romania

the question is
can i buy 255 40 rear and 235 45 front ?
using the same wheels

thanks

400ixl

In order to minimise the difference in rolling diameter you need to drop the width. Otherwise the speedo will be out and the tyres may rub on the arches.

255/40/18 becomes 235/45/18
235/40/18 becomes 215/45/18

You could maybe get away with only dropping one width but you speedo will be further out.

So in gaining some comfort you will lose some grip through narrower tyres.

dudeasca

Oh ok
thanks a lot

Flash Gordon

When I want to change tire size, I usually go to the website of Tirerack. I check out the circumference and the rotations of the sizes that I am interested in. When these two factors of the size are very similar to the original tire size, then I know I got the right one, but I may or may not do it depends my goal and the tradeoff.

retvethogrider

If you go to a 275X30x20 in the rear, the difference in diameter will be negligible. I see no problem with intereference with the taller sizes you want to go to since you are not increasing the width of the tire, only the height.
You should have a more comfortable ride but you will surrender some positive handling characteristics in cornering and, of course, your speedometer will indicate you are going faster than actual speed. But that is really no problem. You can download an app that will give you your actual speed using its GPS. I use Waze. Then you will know the amount of difference.
Hope this helps.