I just got a pair for my front 17x9.5" wheels to replace my RA1's which were about 5-6 years old. I found out now that these things are WIDE!!! lol They hang over i would say at least 1/4" more.

Now that i have red the specs closer these have a width of 11" vs. the RA1's 10.4".

Anyone else run these tires and size on this rim size?

I kinda wish i went with the 255-40-17 which is 10.4".

 

A 17 x 9.5" wheel is about 10.5" wide. The 9.5" dimension is the width between the flanges that hold the tire beads on the rim. Add the width of the 2 flanges and you get 10.5" wide. A 275/40-17 tire fits perfectly on a 17 x 9.5" wide wheel. The stock SS and WS6 cars came with 17 x 9.0" wheels with 275/40-17 tires. I've never heard anyone complain about those tires being too wide. In effect, they would be about 1/4" wider per side than the actual wheel width, which your measurement confirms. That is well within the tolerence of the tire's acceptable range of wheel widths. It also provides you with 1/4" of protection against curb rash.

A 255/40-17 tire is only 25.0" diameter, and that is way smaller than your stock tires (25.7 or 26.1" depending on original size). Wouldn't look too good.

 

I understand your math - but it seems these are a bit wider than 1/4" each side. But i think it might be due to the fact that the 888's tread rolls down onto the sidewall more than any other tire i've seen. I'd say this make another 1/8" wider appearance each side.

Spring is around the corner here so I'm going to mount them on the car soon to see how they look.