Originally Posted By: Jetronic
Originally Posted By: TiredTrucker
Originally Posted By: CT8
2.12% ? if I figured it out properly That is pretty good !
Probably closer to 3%, but same general ballpark as your figure. Improvement was definitely there. And I had put new rubber on the truck in the fall of 2015, so given that newer rubber had a little more rolling resistance than rubber where the tread has worn down in early 2015, that 3% is pretty substantial. Not really sure a 5w30 would make a difference. At full engine operating temp, it is the same viscosity as a 10w30 anyway. Well, AC was on a little, in that it comes on automatically when I switch to defrost mode in winter. But that really is a kind of a moot question anyway, as the engine is having to move 32,500 lb of truck full of fuel with an average payload in the trailer of around 37,000 lb, with a max of 46,000 lb in the trailer. I think turning an AC compressor is chump change in the overall scheme of things for a 500 hp 1750 lb torque engine.
how much thread on the new tyres, versus the old? The miles will be underreportedwith the new tyres, so going by the miles driven the difference might even be bigger than you calculated. But that's assuming you used the same brand a model tyres.
The tires both times same Michelin 445/50R22.5 wide based single drive tires. The old tires had 447,000 miles on them and 8-9/32 when they got pulled off. The new ones started out with 24/32. At the time of the mpg for 2015, the old tires were around 350,000 miles. The new ones had about 70,000 on them mid period of the 2016 mpg comparison.
