Practicality of tire upgrade

[Fat Charlie]

Tire type is more critical than minute differences in tire size, yes, but tire size also plays a role and shouldn't be ignored. Increasing the tire size will affect handling, but not really by much. If you're going to drive so close to the edge that 1/2" of sidewall is going to make the difference, you shouldn't be doing it on public roads (or in your DD).

For hypermiling purposes, especially with an automatic, it's about gearing. Increasing your tire size increases your final drive ratio. It'll also make your automatic downshift sooner, eliminating some of the potential gain and maybe making for worse overall FE. How does your car feel right now, Gone2? Does it shift a lot or do you spend a lot of time with the torque converter locked up? If you're doing a lot of driving close to the edge of downshifting, then taller tires might be exactly the wrong thing for you.

Minor changes in tire size can get you 3% or 4% more distance travelled per wheel revolution by only adding about 1/2" to your tire radius. If changing the gearing on your tires won't send your transmission into lower gears it could be a big help. I went with LRRs that added 0.4" to my radius, so now my car is going 103.4 miles every time it thinks it's gone 100 miles.

[mcrews]

Originally Posted by 2000mc

Don't take it personal Gone2, mcrews is a... scumbag to anyone who has a differing opinion, he's not singling you out, it's just how he is

Actually, my issue is lazyness....not differing opinions.
Fact: his question (of the automatic tranny) is addressed in multiple tests of larger tires. He just didnt want to look and see deeper than the first post.

Instead of checking the link provided and spending time reading and learning, he wants to be spoon feed. There are atleast 4 very well documented larger tire tests with 3 being automatics.

ps. Ive driven a Taurus. I've driven a SHO. BIGG DIFFERENCE. And the best I got out of the taurus was 28mpg. The problem w/ the tauras is it cant be driven 'egine on, in neutral' the tranny doesnt drop the idle.

[F8L]

Like stated above, you're better off choosing a more fuel efficient tire.

I suggest the Michelin Energy Saver A/S. It is available in your size. Michelin Energy Saver A/S

Most tire centers offer a $70 rebate on 4 Michelin tires every other month. That puts these tires at a competitive price point.

[freebeard]

The only connection between the car and the road is the 'contact patch' of the tire (absent a grounding strap, of course). A wider tread helps cornering, a longer patch helps the ride. A softer material helps grip, and thus cornering; a harder material helps lower rolling resistance, and thus helps mpg and hurts stopping distance.

There's a lot to consider. Did I mention hydro-planing?

EDIT: I see there was more than one page. Never mind.