I am about to purchase a set of new tires for my 04 Q/C 4X4. I'm pretty set on the Goodyear GSA. However, I'm considering going from a 245 70 17 up to a 265 70 17. Will this size difference have an effect on my computer in the truck? The guy at the tire shop said the truck came with 2 different sizes.. the 245 and the 265. I trust you folk here more than I do the tire shop. Any input is appreciated.

 

My 03 qc 4x4 currently has 275/70/17 in the wranglers. I'm about to switch up to a 285. Should be plenty of room for you.

 

No it will not mess with the computer in the truck.. I have 35x12.5 R17 Toyo Mud Terrain tires, the only difference is that the speedo is off appx. 4-5mph that's all.. With a 275/70-17 you probably will not see any difference maybe 1-2mph..

 

I'd definitely go to a 285 size tire on a 4x4. So many people tell me my 265's look so tiny on my truck. Thats why I'm going to 325/65/18's after I put my 3" lift on.

 

If you change your tire size the dealer can recalibrate your "computer" to make it correct. The diagnostic computer at the dealer allows them to pick different tire sizes or there is a method to tell the computer how many times the tire turns in a mile. The times turned method allows you to use any size tire and correct the speedometer, but is still not 100% perfect because the formula doesn't always end in an even number and you have to round up or down. But it will be real close.. Most dealers will not use this method because they dont know how to determine the times turned in a mile. To determine the times turned is simple. Take a piece of string and wrap it around the middle of the tire. Either cut it so that the 2 ends meet or tie a knot in it or mark it with a sharpie. Next measure the string end to end or to knot or however you marked it. now comes the math. There are 5280 feet in a mile, if you multiply that by 12, you get 63360 inches in a mile. Take the number you got by measuring the string and divide it into 63360 inches. the number you get is how many times that particular tire turns in a mile. Example 315/70/17 tire is 108 inches around. 63360 divided by 108 equals 586.666666 times turned in a mile. The dealer should do this for free if you bought the truck from them, atleast in my opinion. If you have any questions about this, call me......
David

 

Or get a Superchips programmer and do it yourself, while improving performance!

 

i have 285's on my truck and fit nice, still look small wish i woulda went bigger. Did however notice that the speedo is out about 5 - 10 km/h

 

the idiot i bought my truck from put 240 on mine, they look retarded, 285s are pretty much the biggest tire you can get without a lift or leveing kit, it shouldnt effect your speedometer by more than 5 mp, and seriously if you get a chip for your truck, which i recommend, then it should recalibrate your speedometer for you...

 

Yeah, 240's are a no no! I currently have 285 70 17's on mine with no problems at all. Definitely recommend 285's.

 

much agreement there my friend, and they were the expensive ones from micheline, so ive done pretty much all i can to make them bald so i have an excuse to get new tires, my parents would ckill me if i didnt need tires and i got new ones, cause god forbid i "waste" money on something that i dont need....cant wait til i get the hell outta my parents house....