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Old 12-01-2010, 03:28 PM   #21
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Join Date: Nov 2005
Location: SF Bay area
Posts: 992
My Ride: Sierra 1500 SLT
Originally Posted by MasterC17 View Post
That's exactly what I was thinking except 255/40's on the front - the same as what they came with from the factory except wider. Is there any reason they were taller in the front from the factory? Was it to compensate for the smaller diameter?

Thanks but I already have two sets so I think I'm good for the moment

I have 4 18x8.5 Rear ZHP Wheels. I have two mounted w/ 255/35/18's and two unmounted. I am proposing that I mount two 255/40/18's on the unmounted ones and put them in the front. Why not 255/35/18's? Because the factory had 40's in the front. What I'm confused by is why, and is it fine to do the same. Honestly, I can't afford another set of wheels and tires atm. I'll be selling my all-seasons and other wheels once spring comes. Unless I find a set of Apex 18's for $700 I'll be keeping the ZHP wheels.
The 40 is the sidewall aspect ratio, which is a percentage of the width in cm. A 225/40 is 225cm wide and the sidewall height is 40% of 225, or 90cm. A 255/35 is 255cm wide and the sidewall height is 35% of 255, or 89.25cm. A 255/40 would have a sidewall height of 102cm, resulting in a 1" taller tire and some serious rubbing issues with that width. 255/35/18 all around is the correct combo
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