255/40 or 245/40 on 18" Si wheel - Does it fit?

[CTGT2005]

With just 500 miles on the odometer, I am already thinking of swapping the factory all seasons for a summer performance tire once this awful New England winter wraps up.

Considering going with a 245 or even a 255 with the stock 40 aspect. Some more grip and a little extra cushion at the same time might not be so bad. Some of these roads in the tri-state area can swallow your car whole if you aren't careful.

About 90% of my driving is 100+ mile highway trips. Speedometer might be off a mph or two.

Any fender rubbing or weird sidewall bulge to be expected on the 18x8 rims? Anyone here try a 255/40-18 yet? I used to run 275/40R18's on my mustang way back when on a 8.5" wheel so 255 on an 8" wheel doesn't seem to far fetched.

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[360glitch]

245/40 is fine. Not sure if anyone has tried 255/40.

 

[BarracksSi]

Picked a random 255/40-18 tire on Tire Rack. Its specs recommend a minimum wheel width of 8.5".

I'd just use 245/40.

 

[SandyEggoSi]

You'll get sidewall bulge with a 255, 245 will have the sidewall pretty much no stretch and no bulge. I'd do the 245/40/18. 255 would be too tall aesthetically.

 

[CTGT2005]

Decided to buy one of these wheels to test the fitment. Its a RSR R703 18x8.5" +38mm offset. Should stick out about 10-15mm more than a stock wheel but I read guys run 25mm spacers in the rear and 20mm in the front without rubbing on stock Si wheels. Can anyone confirm?

Same wheel design, different vehicle. Couldn't find any pictures on a civic. Its an aggressive take on a classic spoke wheel. Any thoughts how this might look on a Civic?

Now to figure out the rubber. Decided on 245/40r18. Leaning toward either the Sumitomo HTR ZIII or the Firestone Firehawk Indy 500. Any other suggestions? Looking for value performance.