better mileage with 255/85R16's?

[mtomac]

Has anyone with 255/85R16's noticed increased fuel mileage over the stock 245/75R16's? I'm getting 17-19 empty and 9-11 towing 14-19,000# trailers with the stock tires and was wondering if the 255's would do any better.

Ordered The Juice on 6-17 from Diesel Injection Service. Version 3.5c built on 6-11 just arrived today. Good service & fast delivery from DIS in TX.

[ford2chevy]

Its hard to tell. The speedo is off 5-10mph (about 7 at 70mph) so its hard to calculate. It seems I'm getting under 400 miles per tank when it use to get just above 400, but the odometer is off too. The dealer told me they recalibrated my speedo but they didn't. I'm still at 2000 at 70mph

[SoCalDMAX]

Mike,

I've got 255/85s and I've kept records of every drop of fuel consumed. I saw approx. 1mpg increase in mileage numbers all else being equal.

I used to cruise at an indicated 75-80mph which IIRC was about 2300-2500rpm. Now I drive at the same speed but rpm is about 2100-2200.

With the 255/85s and the Juice, you could tow all day at 65-70mph (~1900-2000rpm) and stay in 5th gear the whole time if you drive smoothly.

That is the ideal setup to me. The tires fill up the wheel wells a little better, get the rpms down a little (9%) and the Juice gives you all the torque your tranny can handle to keep you going as fast as you want (or is safe!) The rolling resistance should be minimally affected and the Dunlop Radial Rover A/Ts (which I copied from a lot of other people on t his forum) ride really smooth, they take out a lot of the little jiggles even at 60-65psi. Thye're a good value, too at about $105 ea. I've got about 7,000mi on em so far and no noticeable wear. I bought a spare OEM alloy and mounted a 5th 255/85 for the spare, which will allow me to rotate 5 tires.

I've got a theory that ford2chevy is getting lower mileage due to his right foot... anybody stacking the Juice and Van Aaken box isn't doing it for economy reasons. ;) ;) You gotta admit, the economy numbers are pretty darn good when you consider the weight of the truck and how much power you're puttin' down from stoplight to stoplight (after the tire smoke clears ;) .)

Regards, Steve

[SWLA]

Ford2Chevy,

How is the road noise with the BFG mud T/A's? As soon as I can wear out the stock firestones I'm putting 255/85's on. I need something more aggresive than these firestones by this fall. I'm looking at several tires available in that size (Trxus MT, Cooper Discoverer S/T, Dunlop Radial Rover RV) that are slightly more aggresive than a standard AT, but fall short of a mud tire. I considered the BFG's but I don't know how much they hum at interstate speeds. What sort of tread life are you expecting?

[ford2chevy]

I have about 5000miles on so far. When I put them on I noticed the difference. I don't notice it anymore. No tread wear noticable so far.

As far as the MPG, my father took my truck to Michigan from Kansas City and notice for every 91.5 miles the odometer reads he is going 100miles. He calculated 18mph going there and 20 coming back. This is with the Juice only on setting 4. He didn't know how to change it to setting 2 and he was in the U.P so his cell phone didn't work. He didn't like driving in the woods, said the accelerator was too jumpy (because of setting 4). He was impressed to say the least with the passing power.

All in all, I think the MPG will go up slighly because of lower RPM on the highway. My tires are 3 inches bigger in diameter and slowed me down quite a bit.

[max out]

When switching to the 255's from the stock 245's do they fit the truck without trimming anything or torsion bar adjustments?

[1BADDMAX]

My mileage seems to be about the same. There may be a 1mpg loss in town, but on the highway it does as good if not better. I only have a slight rub in the drivers side fender well.