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Tire size question


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I've read the post about maximum tire size.  I purchased a set of 17 x 8 Cragars with 4.5bs.  I've been told the maximum tire size I could go on the back is 255/55/17.  Can someone confirm that - maybe someone running the 8 inch Cragar rims in the rear?  I have 17 x 7 rims for the front and was thinking maybe a 235/55/17.  I want to make sure there is plenty clearance in the front for full turn to turn range.  In the past I've had g60-15's in the front and they were too big.  I'm planning on using BF Goodrich Radial T/A white letter.  Thoughts?  I am definitely NOT ok with shaving the lips.

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I have 17x8 with 4.5" backspacing in the rear with 255/50-17 tires. I have 1/2" or less before I hit the quarter lip, so a 275 would be rubbing or very close.

I don't believe they make Radial T/A for 17" wheels.

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A 17 x 8 rim with 4.5" backspace is 0 offset (mounting surface is centered on the rim width).  To keep the wheel/tire combo centered within the available space on first gen Montes, a +6mm offset is needed on the front and a +12mm offset is needed on the rear.  Since your 0 offset rims will push the wheel/tire combo outboard 1/4" (6mm) and 1/2" (12mm) from the center of available space front and rear, respectively, you can encounter outboard clearance issues with wider tires. 

You will be fine with 255/55-17 on the rear and 235/55-17 on the front.  Going to a 275/55-17 on the rear (with those 0 offset rims) will leave you with only about 1/8" clearance with the wheel well lip.  Some may risk that but I personally would not.

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4 hours ago, MCfan said:

You will be fine with 255/55-17 on the rear and 235/55-17 on the front.  

I have 255-55-17 rear and 223-60-17 on front which seem to fir pretty good, no clearance issues.

Only problem is finding the rear tire size nowadays. The only readily available option is a Bridgestone Dueler tire, which from prior experience with that tire is bad. Searches will show a couple from Pirelli, but in reality they're not available at all, discontinued. I thought I found some 2 days ago on ebay from discounttiredirect, but they were mis-labeled and were actually 225-55-17. 

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11 hours ago, MCfan said:

A 17 x 8 rim with 4.5" backspace is 0 offset (mounting surface is centered on the rim width).  To keep the wheel/tire combo centered within the available space on first gen Montes, a +6mm offset is needed on the front and a +12mm offset is needed on the rear.  Since your 0 offset rims will push the wheel/tire combo outboard 1/4" (6mm) and 1/2" (12mm) from the center of available space front and rear, respectively, you can encounter outboard clearance issues with wider tires. 

You will be fine with 255/55-17 on the rear and 235/55-17 on the front.  Going to a 275/55-17 on the rear (with those 0 offset rims) will leave you with only about 1/8" clearance with the wheel well lip.  Some may risk that but I personally would not.

Thanks.  Kind of what I thought.

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6 hours ago, jft69z said:

I have 255-55-17 rear and 223-60-17 on front which seem to fir pretty good, no clearance issues.

Only problem is finding the rear tire size nowadays. The only readily available option is a Bridgestone Dueler tire, which from prior experience with that tire is bad. Searches will show a couple from Pirelli, but in reality they're not available at all, discontinued. I thought I found some 2 days ago on ebay from discounttiredirect, but they were mis-labeled and were actually 225-55-17. 

Yeah I'm finding that size is impossible to get.  I found 235/55/17 (eagle) on walmart.com but no 255/55/17 available.  I've also check cokertires.com.

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47 minutes ago, Katman said:

Yeah I'm finding that size is impossible to get.  I found 235/55/17 (eagle) on walmart.com but no 255/55/17 available.  I've also check cokertires.com.

Last year I think I got the last set of Pirellis in the country. Been looking for an extra set ever since, just to have in stock. No such luck, which means no smoking the tires. Not easy to do with a LS6 454.

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If the factory rim size is 15x7 and tires for them are readily available, why don’t you just go with a taller tire?  17 inch tires are obviously a lot harder to acquire and you may not find what you want. At least with the 15 inch that won’t require any modifications to the car. That would keep you with the stock rim size and keep it “factory “ as I thought that’s what you were going for. Just a thought. I’m not much of a tire guy but it got me wondering. 

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