Without a doubt! I also have a theory that the manual is much better on fuel than the automatic and the US DOT just didn't distinguish it from the automatic... and some proof!

I still have the window sticker for my truck that was issued by EnerGuide (Canada) which states the following... which is very close to my mileage when I had OEM tires.

City: 15.0 L/100Km
Highway: 10.9L/100Km

The US website (Fueleconomy.gov) says

City: 16.8 L/100Km
Highway: 13.1L/100Km


That is a huge!!

 

Manuals almost always always ALWAYS get better mileage than autos. But that mileage you posted is AWESOME for a 5k lb offroading machine of a HUMMER.

So you notice BETTER mileage with 33's as opposed to stock 32's?

 

^^ My truck came with stock 33" tires... I am running 35's now.

But fore sure, much better with 33's than 35's

 

So would you venture to say that 33" tires would get better mileage than say, 32" tires?

 

From everything I have ever heard, trucks get worse gas mileage as the tire size and weight increase.

so by that general, theory.

32s best
33s slightly less
35s even less

 

I couldn't say, it would depend on the gearing... if the 32's make it too short then you spend a lot more time in the higher RPM's. Jrc1122 makes a good point that weight plays an aspect as well.

I would go as far as saying that from what I have observed with the manual transmission; even with the 33's the gears feel too tall... 32's will probably get you better millage.

I really think with 4.88 gears, H3T's equipped with a manual would be way better off.

 

I do a lot of highway travel in the HUMMER so I'm wondering if the taller tires would knock the rpms enough to give me better highway mileage :think: