Tires: Skinny vs Hard vs Weight vs LRR ... - Fuel Economy, Hypermiling, EcoModding News and Forum

lasitter · 05-12-2011, 04:52 PM

I'm working on a project to squeeze the max MPG I can out of my 1996 F150 without doing things that make it a NON-working truck, and I've been thinking about tire related restraints for some time now.

I'm currently running the 235/75R15 tires with a load rating of 2183 pounds per tire, a max PSI of 50 and a weight per tire of 29 pounds. The general category is "Standard Touring All-Season" so the tread pattern is favorable for MPG.

These are non-low rolling resistance (LRR) tires, but more and more of the easy rolling tires are cropping up in various truck categories.

Now one of my options is to reduce rolling resistance by switching to a narrower tire. I've found one that is 215/75R15 that can carry 2095 pounds per tire, giving up only 88 pounds of capacity at a weight per tire of 30 pounds vs 29. The Max PSI is 65, which should be favorable. The general category is "On-/Off-Road All-Terrain" which features a more aggressive tread pattern, that's better for work but not so good for fuel economy.

Finally, I could go for a LRR 235/75R15 "Crossover/SUV Touring All-Season" tire rated for 2271 pounds, meeting or exceeding the manufacturer standard, with a max PSI of 51 pounds and a weight per tire of 31 pounds.

So I'm wondering: What really wins out for low rolling resistance?

Narrower over wider?

Harder (higher max PSI)?

Weight?

LRR construction?

Tire makers are not actually publishing rolling resistance specs for tires now, so I feel that I'm guessing much more than I'd like.

Big Dave · 05-12-2011, 07:25 PM

I've had good luck with Goodyear Fuel Max Tires. The ones on my Impala (235-55-17s) have load ratings pretty close to your current ratings.

Since I put them on the Impala and aired them up to 65 psi, I've gained 1.5 MPG.

Check out the Fuel Max tires. Nothing wrong with car tires on a half-ton pickup.

I keep the E-rated tires on my truck inflated to 100 psi.

redpoint5 · 05-12-2011, 08:05 PM

How important is off-road ability? How about snow? Rain? Tire choice is always about compromise. I had some tires I called the "road warriors" on my 2500 Cummins, and the tread was very unagressive, the tires were narrow, and the sidewall rating was something like 85lbs. They were very quiet, got excellent fuel economy, and performed well in the rain. It was a bit harsh riding with them fully inflated, but that didn't bother me. The problem was that anytime the truck touched damp grass, I was stuck, even in 4 wheel drive.

I have since switched to Bridgestone Dueler AT Revos, and inflate them to max sidewall (somewhere around 55psi I believe). They are taller and wider than stock, effectively giving me a taller gearing. They aren't quite as fuel efficient and my "road warriors", but the compromise is worth the ability to move around in the muck and snow.

For absolute best FE, my suggestion is to go with the largest diameter tire you can fit, as narrow as possible. Then air these up as much as they will go. Of course, the back-end will float around without a load. As to tread pattern; the cooler it looks, the less FE they will likely be (and more noisy).

lasitter · 05-12-2011, 09:40 PM

Quote:

Originally Posted by redpoint5

How important is off-road ability?

It isn't. It just happens that the 215/75R15 tire is also "On-/Off-Road All-Terrain". My main interest in it has to do with it having a 7/10th inch narrower section width, and a 65PSI max. I'm wondering if these two factors could outweigh another tire with an LRR designation.