Best tire size for mileage?

[erikrichard]

My truck came with 265/70/16 Laredo's. Was wondering if anyone has seen an mpg improvement with 245/75/16 or maybe 245/70/16 size tires? I'm averaging just less than 16 mpg combined, would really like to see a solid 17 thinking smaller tires may do it - just wishful thinking?

 

[domin8]

In theory, skinnier tires should do it because their reduced contact patch also means less friction. However, less friction also means less traction. Less traction can be bad. Plus, can a skinnier tire hold the hold of the truck, especially while turning at freeway speeds. What about braking?

Imo, if you value your truck and your life, do a lot of thorough research before doing any tire reductions.

 

[Wake]

You should see a better mpg improvement with larger tires. Larger tires are going to turn slower than stock size and is like changing the gearing to a higher numerical number and a slower turning engine as a result.

My Escalade had 285s on it when I bought it and seemed to get about 1mpg higher before I went back to stock size.

You don't need the full lower end torque of your drivetrain unless you're pulling heavy loads so a slower turning tire won't hurt your power noticably.

With the 285s on my truck I seem to remember the speedo reading about 4-5mph low at 75, so that is something to consider as well. If you have access to a programmer like a Tech2 then you can adjust tire sizes to correct for the speedo but it doesn't have ever tire size selectable in the options. I don't believe 285/70 was an option.

You want to see 17mpg, what are you seeing now? My 05 AWD 6.0L Escalade is seeing about 18mpg on my work commute of 48 miles with out 15 of those being light city driving. I'm pretty easy on the gas pedal though and cruise about 70 mph on the interstate. Above that economy seems to fall off pretty fast. 67 appears to be ideal for my vehicle.

 

[erikrichard]

I guess I had that backwards, taller tires are better. 245/75 are skinnier and lighter but the same height as stock - maybe they will be good for another 1 mpg.

 

[Gzes]

I say dont mess with it. You drive a large suv either way its gonna suck. I would rather live from the right tire then die trying to save a couple $$$

 

[erikrichard]

The 1500 Silverado uses the same 8.5" rims our trucks do, and they use 235s. I seriously doubt there is any safety risk going from 265s to 245s even fully loaded, which I never come even close to doing.
1 mpg equates to $736 savings over 50k tire life based on $4/gal gas, and I would save about $100 on the initial cost of 4 smaller tires. That more than pays for the tires, assuming I get that additional 1 mpg.

 

[domin8]

You should see a better mpg improvement with larger tires. Larger tires are going to turn slower than stock size and is like changing the gearing to a higher numerical number and a slower turning engine as a result.

My Escalade had 285s on it when I bought it and seemed to get about 1mpg higher before I went back to stock size.

You don't need the full lower end torque of your drivetrain unless you're pulling heavy loads so a slower turning tire won't hurt your power noticably.

With the 285s on my truck I seem to remember the speedo reading about 4-5mph low at 75, so that is something to consider as well. If you have access to a programmer like a Tech2 then you can adjust tire sizes to correct for the speedo but it doesn't have ever tire size selectable in the options. I don't believe 285/70 was an option.

You want to see 17mpg, what are you seeing now? My 05 AWD 6.0L Escalade is seeing about 18mpg on my work commute of 48 miles with out 15 of those being light city driving. I'm pretty easy on the gas pedal though and cruise about 70 mph on the interstate. Above that economy seems to fall off pretty fast. 67 appears to be ideal for my vehicle.

I see what you're talking about. You are discussing tire diameter. I am discussing tire width. Both statements are correct. A skinnier tire can improve mpg by reducing friction. A taller tire can improve mpg because it reduces three amount of revolutions the wheel takes to cover 1 mile. Also, it doesn't take a tech 2 programmer to recalibrate the speedo for a different you're size. Aftermarket programmers, such as HPTuners, can also handle this. Which brings me to another idea. Why not get a hold of Black Bear (a vendor on here) about getting a tune for improved mpg. At the most, it'll run the same as a new set of tires, but is likely cheaper.

 

[Wake]

I guess I had that backwards, taller tires are better. 245/75 are skinnier and lighter but the same height as stock - maybe they will be good for another 1 mpg.

I don't know that I would move down to a 245. My Trailblazer used 245/65/17s and I have a set of winter tires left over that I contemplated getting a set of winter wheels to use on the Escalade.

The Escalade weighs half as much again as my Trailblazer did, ~6000 versus ~4000 lbs. I'm thinking your Tahoe/Yukon weighs in pretty close.

You might want to try 285s and see if you see the small gain in economy like I did. I didn't like the way they fit the wheel wells though, looked too full for my stock height vehicle. The slightly taller tire did seem to overcome the extra 20mm of tire tread.