Michelin PSS on Challenge rims?

Hi all,

I have 360 challenge rims, currently running with Michelin Pilot Sports Cups. I'd like to change to Pilot Super Sports but in Europe the largest size available is 265/40R18 (we don't have the 285's). They require a maximum rim width of 10.5" and a section width (on measuring Rim width) of 10.7" on 9.5".

I have the feeling that 265 is too small for the rear 360 challenge rims. Normal size is 295 and I have rain tires of 305 wide. Any ideas?

I could measure the rim width, but where would I measure it exactly? I'm not so familiar with the indications such as section width.

The alternative is to order them from the States (also because 265 is even smaller than the standard 360 size) but I'd have to pay about 16% import tax on them.

Thanks!