[lasitter]

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.