Moderator: volvite
Thanks. Sure makes it that much easier for me to decide. What are the odds that the dealer can re-program the computer to compensate for the tire change? Has anyone tried this? I can live with the mileage being off, as I've had to do that in almost every vehicle I've ever owned. But, it would be nice if it could be corrected.RacerZX wrote:No hesitation at all.
I did some corrected numbers and was able to pull off 20.5mpg in my 06 LE over a 200+ mile, 65mph (for the most part) run with 285/70R17's. That was very little in town driving with a few slow downs for tolls and exit ramps tossed in.NVSteve wrote:I know the on-board computer won't be reflecting the correct totals, but you should be able to get it dead-on using any of the tire size calculators online & a bit of math.
Yea man, but I was Mr OldMan driver to pull that off. Absolutely no goosing it, departing from a stop at very light/leasurely pace. Just cruising. I spent a majority of my time in the slow lane. I didn't mind too much because it only got me to my destination in CT about 15 minutes later than normal but it felt like I was going soooo slow. I also went up 95 for this trip as opposed to the Merritt Parkway. Too many hills on that road.Fofiddy wrote:20.5??? when I went up to the 31.6" my fuel eco became even more dismal. I got 370 miles on a tank once... ah those were the days...
Or this one, which supplies more info: http://www.discounttire.com/dtcs/infoTireMath.dosphantom2 wrote:I thought this may be helpful to you guys http://www.dakota-truck.net/TIRECALC/tirecalc.html
To answer my own question, the service department I visited today said that they can't reprogram the speedo. It was quite a team effort in finding that answer, with the conversation ending up with talk of the vaporware 5" Calmini lift & larger tires. Wonder how they'll react when I bring it in with the modest OME lift installed.NVSteve wrote:Thanks. Sure makes it that much easier for me to decide. What are the odds that the dealer can re-program the computer to compensate for the tire change? Has anyone tried this? I can live with the mileage being off, as I've had to do that in almost every vehicle I've ever owned. But, it would be nice if it could be corrected.RacerZX wrote:No hesitation at all.
Man, do you have your old wheels? Or could borrow a set from someone else, so you can get the true results. Or you going to have to redo all the other tests, with the 33s..RacerZX wrote:One minor downside with these bigger tires is the hit on straight line performance. Sure it's a bit slower due to the gearing change (taller tires = taller effective gearing), but I was surprised to find how much the added weight and rotational inertia effected things. I just had the truck on the Dyno this last Saturday before installing a Gibson exhaust and found only 300HP at the wheels instead of the previous 320.
Now a different dyno on a different day will show some differences, but 20 is beyond the margin of error, and that was only spinning two of these monster tires.
Gibson write-up to come soon as I can get back to the dyno to do a follow-up test...