Originally Posted by Ron94150

265's? Are they stock tires? I thought 245/75 was the only option for 17" wheels. What kind of mileage did you average and what kind of terrain?

Also, check your speedo with gps, my speedo was a few mph slow with the stock 245/75r17's. I bet you will be right at 2150rpm if you go by gps 70mph.

1980 rpm would be if you had factory 20" tires.

Originally Posted by dnewton3

You can either get factory 245/75-17 or 265/70-17. Both have essentially the same tire circumference; close enough that the speedo does not have to be changed.
The diameter of the 245/75 is 31.5", whereas the 265/70 is31.6". That is only a .3% difference. Not 3%, but 0.3%. In essence, in a mile of travel, the smaller tire will only go around 2 more revolutions in the entire mile.

Your tires will see more change in the wear over their lifetime than that of the two choices above.

Originally Posted by ATC Crazy

Those of you with 4.30's and stock tires...what RPM's are you running at 70-75mph, empty, on the highway?

I'm 98% certain I want 4.30's. I rarely drive more than a few miles on the interstate a year...but the occasional 1,000mi round trip to NY is not out of the question. 95% of my driving is 35-55mph roads here in the Appalachian mountains. I also have a 10k equipment trailer I tow about once a month or so.

Originally Posted by Addison86

............Don't you think that's splitting hairs...,,,,.

Originally Posted by Ron94150

Not really, there is less than a 300 rpm difference between 3.73's and 4.30's(don't confuse that little number with a nearly 15% increase in torque leverage). So 50 rpm is a large percentage of that, and also right at 5mph.

I'm using an rpm calculator that uses math to get an exact number, not trying to judge off a large tach with no reference lines.

Originally Posted by DCP

Yes, a lot of people think that the first number is the height of the tire, when it's actually the width of the tire in millimeters. You have to account for aspect ratio when determining the tire's height.

Originally Posted by Addison86

But in real life, where most of us spend our time, 50 rpm doesn't matter. "Oh snap! I'm at 2150! I better back it down so I'm at 2100.."

Originally Posted by Ron94150

When I was 17, and knew it all, I was at a local tire/lube/exhaust shop. I new the owner pretty well, and he was getting up in age. I was getting some exhaust work done on my mustang, and was talking to one of the younger workers about getting some wider tires. As we talked, we began to disagree about which number was width and height. When the owner came by, and heard us, he said, "your both right, and neither one of you know what the hell your talking about".

Originally Posted by DCP

In this age of the internet, it's arrogant to be ignorant.

Originally Posted by ATC Crazy

Those of you with 4.30's and stock tires...what RPM's are you running at 70-75mph, empty, on the highway?

I'm 98% certain I want 4.30's. I rarely drive more than a few miles on the interstate a year...but the occasional 1,000mi round trip to NY is not out of the question. 95% of my driving is 35-55mph roads here in the Appalachian mountains. I also have a 10k equipment trailer I tow about once a month or so.

Originally Posted by DCP

With the six speed transmission, the 4.30 gearing works well at any speed. IMO, 6.2L trucks should come standard with 4.30s. Stating the obvious, gas motors don't produce the torque of a diesel, so gas motors needs all the mechanical advantages that they can get via, lower gears. I run the stock 245/75/17 tires.