Questions on towing with a lifted truck
First off, this is such a great site. I did a ton of reading and research and it totally Influenced me to go out and buy a brand new GMC 3500HD and a 35ft travel trailer. I've never owned or even towe...
Forum Discussion
BurbMan wrote:
Also be aware that taller tires will effectively decrease your axle ratio. Formula is the old tire diameter divided by the new tire diameter times the axle ratio. For example, I have 4.10's on my truck, and when I swapped out the factory 245's for 265's, the larger diameter tires reduced my axle ratio to an effective 3.92. I noticed it right away in that the trans wanted to downshift a little sooner on hills, and that's towing 8500 lbs. I wanted a little more ground clearance and traction off road, but didn't go to 285's because I didn't want to decrease highway towing performance that much. So the 265's were a good compromise for me. If I was hiway all the time I would have stayed with the OEM 245's. If I was offroad more of the time, I would have gone with 285's.
The tire size you're referencing is the width, not the height.
FWIW, on my '07 Silverado 1500, I went from 245/70 (stock size) tires to 285/70 tires at my first tire change. The truck improved in every way. Better mileage, better handling, better ride, etc. Nothing changed regarding shifting. The speedo is off by about 3 MPH when it reads 75 MPH. Below that, its negligible.
