255/75/17 Or 265/70/17

Madcap · October 26, 2007

I thought I convinced myself to upgrade from a 245/70 to a 265/70 tire but than I noticed the Bridgetone Alenzas which make the 255/75 tire. I used a tire calculator, and it seems to be a bit taller. (which I'm looking for) Is there any downside to this tire, because I noticed it's not a very common size.

I'm looking for the biggest tire I can get other than a 285, because I doubt my truck would fit that. I have a 2WD Also, so I don't need anything too aggressive.

Paul58 · October 26, 2007

I thought I convinced myself to upgrade from a 245/70 to a 265/70 tire but than I noticed the Bridgetone Alenzas which make the 255/75 tire. I used a tire calculator, and it seems to be a bit taller. (which I'm looking for) Is there any downside to this tire, because I noticed it's not a very common size.

I'm looking for the biggest tire I can get other than a 285, because I doubt my truck would fit that. I have a 2WD Also, so I don't need anything too aggressive.

I have Bridgestone Alenza 255/75-17's on my truck and really like them. I was going the same route you were and discovered through my research and the tread width (rubber contact patch with the road, not side wall width) was actually wider by a couple mm on the 255/75-17's than most 265/70-17's, and were significantly taller! The Alenza's have a quiet comfortable ride and look 100% better than the stock 245/70-17's. I bought mine through Indy Tire, and they gave me a credit of $61.00 per tire for the stock tires. I replaced all 5 and saved $305.00 on my purchase! Call around, find the best price and then ask if they will give you a credit for your stock tires. I had about 150 miles on the truck when I changed tires.

One other thing to be aware of, the taller tire size does change the rear drive ratio. My truck has the 3.73 rear end, so the rear axle ratio with the taller tires is now 3.55. The taller tires will throw off the transmission shift points, the speedometer and odometer, but that can be corrected by a trip to the dealership, or an aftermarket programmer.

07Graystone · October 26, 2007

I thought I convinced myself to upgrade from a 245/70 to a 265/70 tire but than I noticed the Bridgetone Alenzas which make the 255/75 tire. I used a tire calculator, and it seems to be a bit taller. (which I'm looking for) Is there any downside to this tire, because I noticed it's not a very common size.

I'm looking for the biggest tire I can get other than a 285, because I doubt my truck would fit that. I have a 2WD Also, so I don't need anything too aggressive.

Although Bridgestone does not make this size, consider a 275/65R17. They are 1/2 inch taller and 1 inch wider than a 245/70R17. They look great on a factory aluminum wheel and fill up the fender well without having too tall of a sidewall. I'm very happy with mine.

Madcap · October 26, 2007

I thought I convinced myself to upgrade from a 245/70 to a 265/70 tire but than I noticed the Bridgetone Alenzas which make the 255/75 tire. I used a tire calculator, and it seems to be a bit taller. (which I'm looking for) Is there any downside to this tire, because I noticed it's not a very common size.

I'm looking for the biggest tire I can get other than a 285, because I doubt my truck would fit that. I have a 2WD Also, so I don't need anything too aggressive.

I have Bridgestone Alenza 255/75-17's on my truck and really like them. I was going the same route you were and discovered through my research and the tread width (rubber contact patch with the road, not side wall width) was actually wider by a couple mm on the 255/75-17's than most 265/70-17's, and were significantly taller! The Alenza's have a quiet comfortable ride and look 100% better than the stock 245/70-17's. I bought mine through Indy Tire, and they gave me a credit of $61.00 per tire for the stock tires. I replaced all 5 and saved $305.00 on my purchase! Call around, find the best price and then ask if they will give you a credit for your stock tires. I had about 150 miles on the truck when I changed tires.

One other thing to be aware of, the taller tire size does change the rear drive ratio. My truck has the 3.73 rear end, so the rear axle ratio with the taller tires is now 3.55. The taller tires will throw off the transmission shift points, the speedometer and odometer, but that can be corrected by a trip to the dealership, or an aftermarket programmer.

I think I have the 3.23 rear end (is this a true spec) which I'm not even sure what that means. I know nobody likes rear ends with specs this low, but this is what I think I have. I get pretty good gas mileage, I can run 80mph at 2K RPM's, and I don't tow anything. If I got taller tires, and it lowered my rear end what will this mean in terms of performance? Weird tranny shifts and 100mph cruises at 2k rpms? lol

badmeds · October 26, 2007

You didn't ask, but you might also consider Bridgestone Alenza 275/60-17's. These will be my next tire as soon as the stock ones have a few more miles. I have a 3.42 rearend and want the lower profile for performance and handling since I drive mostly highway. I ran 275/60/15 on my '89 and 285/60/16 on my '99. 60 series tires will have a stiffer sidewall. These size tires are a good bit wider but only about 1/2 inch lower than stock so your gear ratio would be changed to a higher number.

Good luck with your decision.

Paul58 · October 26, 2007

It's hard to say how it will effect you performance and gas mileage. Performance (off the line) will probably suffer, and gas mileage may as well because with lower rpms you're getting below the optimum power band and the engine actually works harder to propel the weight of the truck. Another factor that comes into play is aerodynamics, a taller truck is a larger surface area to push through the atmosphere!

I had an F-150 with 3.55 gears and a 4.6L V8. I went from 275/60-17's to 265/75-17's and my gas mileage dropped 3 mpg! I did not notice that drop with this truck, but I had a lower rear gear to begin with.

Paul58 · October 26, 2007

I ran your tire sizes and gear ratio through the gear calculator in my Edge Lightening program.

If you currently have 3.23 gears, your effective rear ratio will be 3.07 after installing the new tires. To get it back to stock, you'd need to install 3.39 gears.

If your rear drive ratio is 3.42 then after installing the taller tires your effective rear ratio will be 3.25 and you'd have to install 3.58 gears to get the stock rear ratio back.

Or, you could install 3.73 or 4.10 gears which would give you a rear ratio of 3.55 or 3.90 respectively! Either of these would improve your off the line performance over your current stock set up.

Hope this helps...