Quote:
|
I'd really like to get back to what I originally asked, about the difference between 7.2" and 6.2" ... any guesses as to what downsizing might mean?
|
I will need to extrapolate from a vehicle that weighs about 1 ton. That said, and assuming your F-150 is 2WD, this may apply.
My stock tire size would be 165R-15. Following the lead of street rodders (big-n-littles) and Cal-Look VWs I downsized to 145s in front for years. With RWD the engine RPMs don't change (althought the speedo run off the left front wheel is a different matter). Caster is affected. Narrowing the tread relative to the rim width does a number of things. Mileage up is the one you're looking for. The narrower tread presents a smaller 'attack surface' for road irregularities. The tire/wheel edge is more aerodynamic. Road feel improves, and what's called 'turn in' improves. That's how long it takes for the tread to respond to input at the steering wheel.
OTOH you may also find that in downhill runs, you may have more brakes than traction. Plus weight transfer from the rear. I've gone to a Federal Formosa 165-50R 15. They sell sizes in 10mm increments in size and .05 increments in aspect ratio. Carrying capacity varies with aspect ratio.
I don't know if they have a tire that fits your need. But that's the kind of choice you should have available. Here's the tire I want:
Bridgestone Ecopias on 4x19" rims. I heard Rolls Royce used a 30" tire on 4x19. Coke Tire may have them.