AT4 - MPG Issue & Tire PSI on new Nitto Ridge Grappler Tires & Fuel Rims

[amxguy1970]

45 minutes ago, newdude said:

 

The tire you've put on is 59.08lbs.  The Duratracs in OE size are 49lbs, so a 10lbs difference per tire.  The tread design is more aggressively interlocked than the Duratrac so that would add resistance there alone.    

 

Not sure what Fuel wheel you picked, but you've also gained 10+lbs minimum per wheel.  OE wheel that came on your truck is 30-31lbs.  Some of the Fuel 20" wheels I was looking at scaled at 49lbs.  

 

What I'm going to suggest is this.  Stop by your local dealer with the information below.  Short story is that if your truck could have been optioned with the 20" wheels from the factory, which on the AT4 is possible, that GM would be able to issue a calibration file that the dealer can then flash your truck with.  The stock 20" tire is the same size you put on, 275/60R20 so GM would have a calibration to do that.

 

If doing this doesn't get everything back to about where you were before changing to what you put on the truck, then I'd be looking at the tires you put on next.   

 

 

It doesn't matter if the truck had the 20 inch option or not, he won't gain back that mpg versus where he was before. It probably corrects the small percentage of the calculation that is tire size difference, which equates to less than 1/2 mpg, so instead of 12 he may be showing 12.5 mpg with the computer adjustments. Fact is he still added 10 lbs per tire and probably 10 lbs per wheel if not more over stock, he will lose mpg especially if he does more city driving; he is now more up in the air as well which reduces his highway mpg. The ridge grapplers are just as aggressive as the duratracs, so the tread itself isn't much of an issue, but hte stock 20's come with a much more street and mpg friendly tread pattern. Honestly it is just another guy that didn't thoroughly do their homework and are shocked when they take an mpg hit with a new much heavier set up; it costs money to look cool...

 

Tyler

[gearheadesw]

As all have stated, heavier tires, heavier wheels, all in the wrong places. Big hit on milage here.

[eppieguy]

4 hours ago, JerseyMikeAT4 said:

Maybe a stupid question but is comparing my speedometer to to using Waze and another GPS device (they all report the same) sufficient? 

Yes, I was under the impression that you increased tire size in which would throw off your speedometer. It’s got to be the heavier tires and wheels as others have said. 

[Jav_eee]

Is 40 PSI considered too much air?  

You should always do the chalk test to set the correct psi. Google it.

Also, I lost 2.5-3mpg going from the stock 34” to a 35” tire on my F250 with the powerstroke. It happens.


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[Memphis87]

On my 19 TB i put 305/55/20 ridge grapplers on a set of 20x10 fuels and went from Over 20mpg average to 17.1mph. It’s also be stated the AT4 gets worse mpg than the TB from the get go, but damn 13mph is rough