Tires&mpg: tall for tall gearing, or small for less rolling resistance?

[Hohn]

Well, here's the issue: which tires give best mpg? Is it better to go to a taller tire that drops gearing but has more rolling resistance? Or a smaller tire that is shorter gearing, but less resistance?



I think it varies with tread pattern as well. A small tire with aggressive tread might have more rolling resistance than a tall tire with hwy tread. Or is it the other way around?



I mean, what would expect to happen to mpg if I went from the 265 Micheling A/S to a 315 Pro Comp A/T? What about a 285 Mich m/s? A 265 m/t?



Right now I'm leaning to a bigger 315 tire with mild tread, like a Cooper ATR or Procomp A/T.



What say you? What has your experience been?

 

[JJW_ND]

Slightly taller but Narrow....

I have had great luck with 235/85R. Not much taller then 265's but taller then the 245s that were on mine. Im running 255/85R now. I still get very good milage (low twenties when all HWY). The narrow tire helps with the rolling resistance.



If you want good wear, make sure what ever you get is as close to the sweet spot for the rim width. Each tire will give you an acceptable range of rim widths with a bold value that is optimim. The closer you are to this number the more miles, less noise, and lack or tire issues you will have.



jjw

ND

 

[Smokin_Monster]

When I bought my truck it had 245/75R16s on it and I averaged about 14 mpg/city - 16 highway (I have 4. 10 gears). I put 315/75R16s and now I average 16. 5 - 17 city / 18-19 highway. I can't complain.

 

[Clinton]

I agree with both responses. I'm a 4. 10 driver and noticed improvements when I went to a 235/85 (BFG A/T... not a long lasting tire) and again when I went up to a 255/85 (Toyo M55... best tire I've ever owned). I started out with the stock 245/75 (Goodyear Wrangler). I won't go any larger than the 255/85 Toyos because I don't want to spend on wider wheels, which I believe would be necessary for safety.

 

[Boondocker]

resistance is futile

I don't know what affects MPG more - tire rolling resistance or aerodynamic drag. Certainly, the taller the vehicle (frame to ground clearance), the more turbulence is created under the chassis. That's why cars that go fast are low to the ground and have front valances or spoilers that hug the pavement.



Larger tires also have more inertia. They require more energy to start rolling and to stop rolling. If you do a lot of short trip driving, this may factor higher than highway performance where just maintaining rolling speed is less of an issue.



If you go too far from stock, you may want to consider speedometer correction.



Finally - tires and wheels are the single most important factor in a vehicle's appearance. So if you're having trouble deciding based on personal recommendations, empirical data, and considered speculation, try some on for size and see if the appearance influences your decision.



I have about 55K on my stock 265/75 Michelins and expect to get 60K out of them. They've worn well, fit the wheels, I have a matching spare, and I need E-rated. So when it's time, I'm going to bop on over to my nearby Discount Tire and get new set. I'm not even shopping around. That store has been real good to me with free flat repairs and general customer service, so my business and my tire choice is in the bag.



Neil



Cummins ISB - the joy of SIX

 

[Matt400]

From 285 Toyo's to 315 Coopers we saw a 2 mpg decrease on the 03 and that includes a recal of the speedo.

 

[Underwood Tire]

tires

a 285 75 16 and a 305 70 16 are basically the same hight. please keep in mind with 354 gears you are not turning many r. p. m. (70 mph is around 1900 rpm)

this is a great gear if you are on the enterstate all the time. when you increase the hight of the tire you will be lugging your ctd at 55. or you can keep it in 4th or drive when running in the country or city. lugging the engine makes heat and less mpg. i would stay with the 265 if this is the case

good luck

joe

 

[Bob4x4]

On my 05 with 4. 10's I was a bit suprised I lost 1 full mpg when I went to the 315's. The 3rd gens just like to run at a higher rpm. My 94 with 3. 54's is very happy with its 315's and is still able to get over 20 mph while running rings around the 05... ... ... ... so far



Bob

 

[Coolslice]

I lost 3-5 mpg when I switched to the 35" Toyo MT's. I got them off asap and went back to stock, and with fuel prices they way they are, I think it was just common sense.

 

[RustyJC]

Justin,



While the 4. 10 trucks might benefit from a taller tire, I've seen many reports that the 3. 54 trucks lose mileage when a taller tire is fitted (although there are exceptions, I'm sure).



If I were looking for a long-wearing, low rolling resistance tire, I'd see if the Michelin XPS Rib is available in the size you want.



Rusty

 

[Diesel Nut]

I am running 265 70R19. 5 tires that measure in at 34. 6" tall, in duals, and 3. 73 gears and run around on the hwy at 20 mpg all day long. Last tank, hand calculated was mixed driving, 75% hwy/25% city, 18. 78 mpg. And the speedo is dead on with my gps. Narrow, tall tires, and don't be afraid to inflate them. Low pressure may ride nice but all it does is increase rolling resistance, worse when loaded or towing. When I had my stock tires I ran them at 80 psi in the front and the duals were 75. I tow a lot and was loaded alot so it made sense.

 

[LOtero]

I've got 3. 54's and 315's had 265's before. I figger lost a little power off the line with the seat o'the pants meter, not a whole lot though. highway driving is nice now lost about 400 rpms cruising at 80 2200 to 1800. best highway is 21 and city average 16/17

 

[griggsd]

With mild mods on a 00' 6spd with 3. 54's I've averaged the following combined mileage 265 Michelins/19, 295 BFG AT's /20. 5, 315 BFG AT's/17. 5. Exceeding 33" will affect your mileage.

 

[pwknapp]

I also run 4. 10's. Stock '96 came with 215's. Put 235's on before it left the dealer. Two years ago went to 255's and jumped 3 mpg highway and 2 mpg in town. Just ordered a six pack of 305/85/16's @ 36". Hope these will bump it up another couple of mpg. We'll see.

 

[drrhoades]

pwknapp



What 255's were you running and at what pressure?

 

[sam616g]

Just ordered a six pack of 305/85/16's @ 36". Hope these will bump it up another couple of mpg. We'll see.

What brand tires are those?

Thanks.

 

[Dl5treez]

If you stay with a tall & skinny tire you can capitalize on the higher effective final drive ratio without the trade off of a wider footprint, and the increased rolling resistance and turbulence it creates.



Unfortunately with metric sizing it's rather difficult to come up with tall tires that are still narrow.

 

[Hohn]

What brand tires are those?

Thanks.

Probably Denmans. I don't think anyone else makes a 305/85/16

 

[Hohn]

If you stay with a tall & skinny tire you can capitalize on the higher effective final drive ratio without the trade off of a wider footprint, and the increased rolling resistance and turbulence it creates.



Unfortunately with metric sizing it's rather difficult to come up with tall tires that are still narrow.

Maybe Ricksons would offer better options in this area?

 

[CumminSense]

If you stay with a tall & skinny tire you can capitalize on the higher effective final drive ratio without the trade off of a wider footprint, and the increased rolling resistance and turbulence it creates.



Unfortunately with metric sizing it's rather difficult to come up with tall tires that are still narrow.

I haven't gone away from stock yet, but have researched some for MPG and agree with somewhat tall/skinny. Don't forget tread -- I think there was a Cummins paper that said 60 - 70% of rolling resistance is in the tread. Go to a summer ribbed pattern, that's a big savings. I think concensus was Michelin XPS Summer Rib was excellent as skinny/min tread/tough/E range, but pricey. Search on XPS, I think there's a thread or two out there on tires for MPG.