Quote:
Originally Posted by Presario
I’m going off of tirerack’s tread width measurements for those tire sizes. 275 tire is of course wider bc it’s in mm but the contact of the tread is wider for the 265 40 on the P4S than the 275 35 P4S. That’s all I’m sayin. Can’t explain it.
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You are looking at the 275/35/21 which is a Mercedes Benz special tire so they may have some funky measurements and it is listed as tread width less than 265. If you look at the 275/30 it is 9.7" tread width.
If anyone wants to stick with PS4S, there are currently no good options available for upsizing tread width on 21" wheels while keeping close stagger and equal diameters front to rear. This may be a large reason why the spec is 255 front and 265 rear. It's what's available for PS4S on 21" wheels at ~29" tire diameter.
You could fit 295/35/21 on rear but then what do you put on the front? 255/40 is closest diameter but 40 mm stagger which may be fine but is far from OEM design. 265/40 probably works but then you have a slightly larger diameter tire in the front and still 30 mm stagger. OEM setup is 1.1% taller in rear vs front. If you run 265/295 then you swap and have front tire 0.8% taller than rear. Maybe this makes no difference or maybe it messes with the xDrive and traction control.