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Posted

I'm not sure about those specific sizes but there's a comparison tool on rimsntires.com that makes it pretty easy to see the difference between wheel and tire sizes.

http://www.rimsntires.com/specspro.jsp

Appreciate the link. Some good info on it for sure. However I was looking more to see if anyone had already tried a 305 55 20 with the oem wheels and what the results were. I saw one with toyos but none with nitto.
Posted

Finally got my wheel/tire setup installed today!

Is your truck iridium metallic?

Posted

20x9 XD Hoss -12 offset. 285/50 terra grapplers. Wanting to do 305/50 or 305/55 next. Got a decent deal on this set used.

20150225_162627_zpsvcz3j05z.jpg

Love this color!!!
  • Like 1
Posted

Awesome that's the same thing as GMC's iridium metallic. I've been wondering what my truck would look like with athracite wheels. It looks awesome.

 

Anymore pics?

Posted

5RWill suggested I post my question in here, so copied it and posted it below.

 

Some folks have been talking about tires, and my question is; is there a way to tell the computer that the tire diameter has changed? I have suspected that folks experience mileage loss on a bigger tire may be due to not accounting for it in the speedo and therefore the trip calculator shows a drop. The reason I say this is that when a 31" tire travels 5280 feet (a mile), it gets there in 650 revolutions, but a 33" tire gets there in 611 revolutions (not accounting for slippage or bumps on the road).

 

So a truck with the smaller fires would still be traveling when the one with the big tires completed the mile (all things being equal).

 

Is my logic sound?

 

Of course, you can let the GPS tell you what speed you are traveling at and compare that to the speed-o-meter. If you are traveling faster than what the speedo shows, then you are also covering more ground. And that has to be accounted on the mileage calculation (and that goes even if you ignore the co puter and do the Ol trusty "fill-up-tank-then-travel-a-distance-and-then-fill-the-tank method). :)

 

GerryLP :cool:

Posted (edited)

Yes, you can update the computer settings to account for different size tires and thus a different count of rotations per mile. There are many programmers available to consumers that allow us to update the computer settings ourselves but the dealer can also update the settings for you. Buying a programmer will cost you $300 to $500 depending on which you get.

On the '14 and up, if you take the vehicle to a dealer for service, GM can see that you've updated the programming and could void all or part of your warranty depending on what settings you changed if they contributed to a failure of some kind. On the older vehicles, if you reset to factory settings before taking it to a dealer for service, they couldn't tell you'd done anything to it.

The local dealer to me it would be a bout $50 to $60 for the shop time to have them re-program my truck for a different tire size and any dealer would be far less likely to squawk about the warranty because it was just tire size and a dealer did the work.

I'd fight tooth and nail if they tried to void my warranty because I adjusted tire size settings myself but, at the same time, paying them $60 vs. spending $400 for a programming is fine by me. Once my warranty is up, I'll get a programmer and tune the motor, remove speed limiter, etc. but on a new model year vehicle and with some of the issues others have seen, I'll avoid risking warranty coverage!

 

As for mileage, a larger tire, and particularly a heavier 10 ply LT tire vs. the 4 ply P rated stock tires, means more rotating mass and therefor more power/fuel required to get move the vehicle. This is generally why there's a fuel economy loss when going with larger tires.

That being said, my '03 had 4.10 gearing and going with a 285/75R16 actually yielded better mileage than the stock 265/75R16 because my motor was at a lower RPM for the same speed and therefor using less fuel per mile.

 

5RWill suggested I post my question in here, so copied it and posted it below.

Some folks have been talking about tires, and my question is; is there a way to tell the computer that the tire diameter has changed? I have suspected that folks experience mileage loss on a bigger tire may be due to not accounting for it in the speedo and therefore the trip calculator shows a drop. The reason I say this is that when a 31" tire travels 5280 feet (a mile), it gets there in 650 revolutions, but a 33" tire gets there in 611 revolutions (not accounting for slippage or bumps on the road).

So a truck with the smaller fires would still be traveling when the one with the big tires completed the mile (all things being equal).

Is my logic sound?

Of course, you can let the GPS tell you what speed you are traveling at and compare that to the speed-o-meter. If you are traveling faster than what the speedo shows, then you are also covering more ground. And that has to be accounted on the mileage calculation (and that goes even if you ignore the co puter and do the Ol trusty "fill-up-tank-then-travel-a-distance-and-then-fill-the-tank method). :)

GerryLP :cool:

Edited by Hozer
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