Dynocon

I am looking at a new truck. 2500 Quad Cab Long bed 4x4 with a 3:73. The dealer said that he would change the tires to what ever size I want. What would be the best size for better MPG running 45 - 80 MPH? I know the old trucks had a 3:55 option, would 285's tires with a 3:73 be equilivent?

BigBlueDodge

you would need to step up to something a little higher I would think. The Nitto Terra Grapper 297/70/17 or Goodyear Mud Terrains at 305/70/17 would put your right about there.

A 285 tire over the stock 265 tire is a marginal change. For best MPG, you would want something tall and skinny. If only they made a 255/85/17 .....

BigBlueDodge

Did some calculations with some online gear/tire calculators and found that the 295/17/70 are pretty much the exact size to get you to the 3.55 ratio. Using a base of 265/70/17 with 3.73 rear end, and going to a 295/17/70 size gave an effective gear ratio of 3.5445. The 305/70/17 gave a ratio of 3.4867

RamWheelsBy4

It is going to depend on what kind of driving conditions you are in. City stop and go driving will be worse with any larger tire. My 315s with the 3.73(Think it is about 3.43 effective ratio) lost 1-1.5mpg city driving. They are about the same mpg on the highway.

Heavier tires, more tire to pavement resistance and more wind resistance the taller you get seems to be a wash on the highway and cost you in city driving. That is what I have calculated with my truck and tires. Just my .02.

Dynocon

The dealer recomends going with the 275s. they are 32.7" tall vs the 265s which are 30.5". This should effictively change the ratio from a 3:73 to a 3:48.
The dealer said that the 285s are only like an inch taller and 2 inches wider.

sherman

Going to a wider tire will cost in mpg by increasing the foot print,eep the tire high and thin.Try not to go beyond 235/80.

Badd Dogg Guy19

I think once I pick up my truck, Im gonna get an 18x9 rim, and prob get either a 285 or 295 tire. I think the tire combo that comes on the 2500's are a little too small, They just look tiny in the wheel wells. I think going with an 18" wheel, and a 295 tire, will keep close to the stock set up, but will only be an inch wider, and around 2-3 inches taller/ Hopefully those sizes wont affect gas milage alot, but will make the truck look a little better.

P.S. I will prob be selling my stock tire set up once I get the truck, tires will prob have less that 200 miles on them.

jkitterman

If you want better mileage, you need to go with a rib style tire not an AT or Mud tire. Look at the Michelin XPS rib. That tire, although it doesn't come in the correct size, will give you a lower rolling resistance. Generally, the wider the tire, the worse the rolling resistance.