What Tire Size ?

5RWill · December 1, 2014

295/55/20 or 295/60/20 would be my choice. Was settled on 33x12.5x20 but i think 12.5 width is too much for me. Love the way 11.5 looks in a 33-34" tire.

Spurshot · December 2, 2014

An 11.5 x 33 should be an easy fit. Keep the offset close to stock.

DanielAcosta · December 2, 2014

I have a GMC AT right now with 275/55/20. I have a 2in level up front. My question.. If I want a tire that is a littel bit taller.. and a little bit wider.. what would be the perfect size?

My AT rims get curbed real easy... I would like to get a tire that is a little wider to protect them better. Also a little taller since I have a 2in level...

I'm running 34's, look in my signature block.

TX_AT · December 2, 2014

I went with height over width. Open Country M/T 275/65/20. Per Toyo specs (34.5 x 11). 11" is same as stock.

5RWill · December 2, 2014

Looks great, how big of a hit did you take on gas mileage?

TX_AT · December 3, 2014

After 7k on them I average approximately 15hwy / 13city. Normal driving & 75 on hwy. @ 70 u get better mileage but I feel it takes me much longer to get to where I need to go, even though it really doesn't. I've read many posts on here where some are still getting way better mileage but I guess I'm not as lucky.

5RWill · December 3, 2014

Ouch 13-15 city is pretty normal for me but 15 highway would be taking a hit. Was thinking about 295/60/20 like my cousin has but I'll probably stick with 295/55/20

DanielAcosta · December 3, 2014

After 7k on them I average approximately 15hwy / 13city. Normal driving & 75 on hwy. @ 70 u get better mileage but I feel it takes me much longer to get to where I need to go, even though it really doesn't. I've read many posts on here where some are still getting way better mileage but I guess I'm not as lucky.

That's terrible mileage, I'm still getting 20-22 running 34's. Have you corrected your speedometer/odometer for the oversize tires? If not, that should help your numbers tremendously.

5RWill · December 3, 2014

That's terrible mileage, I'm still getting 20-22 running 34's. Have you corrected your speedometer/odometer for the oversize tires? If not, that should help your numbers tremendously.

How would one do this? Just curious?

DanielAcosta · December 3, 2014

How would one do this? Just curious?

Hypertech.

Spurshot · December 3, 2014

That's terrible mileage, I'm still getting 20-22 running 34's. Have you corrected your speedometer/odometer for the oversize tires? If not, that should help your numbers tremendously.

You're getting better economy than anyone else I've heard about with o/s tires. What type of driving?

TX_AT · December 3, 2014

That's terrible mileage, I'm still getting 20-22 running 34's. Have you corrected your speedometer/odometer for the oversize tires? If not, that should help your numbers tremendously.

Nope not corrected but hwy speed is approx 5mph over what it shows, 70 is actually 74-75. All mileage/mpg is hand calculated and recorded on an app. The cluster shows it a bit different. I didn't want any warranty issues so I stayed away from the hypertech or any reprogramming route. I know that's a whole different topic but I'm pretty sure that's why ur getting such good mpgs. I was barely getting that out the dealer.

DanielAcosta · December 3, 2014

You're getting better economy than anyone else I've heard about with o/s tires. What type of driving?

Routine driving, nothing special. The difference is the programming that allows upshifting and V4 operation the way the truck was designed. If you run oversize tires and don't correct the ECM, shifting is delayed and V4 operation is inhibited because the truck thinks you have a big load because your indicated speed is lower than it should be for conditions.

It's still a truck, so the mileage still drops above 70-75 mph. I rarely get over 22mpg for a tank because I cruise closer to 80 than 70. My best 400 miles per the DIC is 22.9, my overall average for my first 34K miles is 20, which has been pretty consistent since day 1.

Easy cruising around town between 40-60mph always yields the best mileage of 22-24, stop and go traffic it drops to 18, sometimes as low as 16. Overall I do about 500 miles per tank with an overall average of 20.

Bottom line is if you're running oversize tires, invest in a Hypertech speedometer calibrator. My dealer's service dept and manager has blessed it, too, because I'm only correcting the speedometer as opposed to trying any aftermarket tuning mods. Fixing the speedometer is all the truck's factory program needs to correct shifting, V4, etc. to match the way it was designed.