my DS original tyre is 235/50/r20, now is 255/45/r20, can I option with a 265 tyre? In my impression the 8j wheel can max support 265 tyre.

Try this for size

Low profile tyres are very fussy as to the width of rims that will accommodate them, the lower the profile, the more fussy they become. The reason is due to the side wall, or lack there of. When using a higher profile, there's a large amount of tolerance, as the sidewall will simply expand or contract to fit the rim. A low profile tyre doesn't have sufficient side all to accommodate big changes in rim width, so they are restricted to using rim widths which keep the side walls perpendicular to the tread. Not doing so will reduce grip and increase tyre wear to unacceptable levels.
For reference, my wife's Audi A5 S Line Convertible has 9 X 19" rims as standard, fitted with 255/35/19 rubber. The side walls are perpendicular to the treads, which is how they perform best.

Fitting a 265/35 to an 8" rim would result in the tyre running in the centre of the tread ( called ballooning), which isn't good for life or grip.

how about original rim 265/45/r20?

dk2020 said:

how about original rim 265/45/r20?

Click to expand...

Use this calculator to work out what tyre fits on what rim.

8" rim, 265 tyre roughly 10 1/2 inches the tyre will go on & will bulge on the sidewall.
Ive got 315 tyres on a 10" rim but I have bead lockers & the tyres have side wall protection, low profiles will pop
in the first decent pot hole as they will nip the tyre as it squishes.