Tire Size and FE question

[GMKing]

I've got quite some time before I need new tires, but that just means more time to save up for some good stuff,

before I begin trying to plan which tires and wheels I want I was wondering how exactly does tire size (both height and width) effect FE?

example, if I go with a taller than stock then my acceleration should decrease but my top speed should increase, which means that the revolutions of the engine are each individually pushing the vehicle just a bit further due to greater tire size.

if I go with a smaller tire than the converse is true. however, the engine techinically needs to work harder to move the taller tire than the smaller tire, so I'm wondering where does FE fall in? taller tire and greater FE or smaller?

also, width of the tire, I can only imagine that going wider increases drag both from air resistance and creating a wider contact patch and therefor increases rolling resistance. but I might be wrong.

as for the rims, my only plan is to stay with 15's or maybe go to 16's but no more, and to obtain the lightest set possible cause low unsprung weight is good good good. Thanks for all input

[GMKing]

oh come on, no FE experts out there to help me out?

[1stToyota]

Anything wider, stickier, and any combo with more rotating mass will hurt the FE, but I'm no expert so don't ask me for what tire/wheel combo works best, and if you have ABS I wouldn't think about altering the tire's overall diameter.

[supmet]

Originally Posted by GMKing

example, if I go with a taller than stock then my acceleration should decrease but my top speed should increase, which means that the revolutions of the engine are each individually pushing the vehicle just a bit further due to greater tire size.

Most of that is true, but a taller tire means it will probably deform more, which takes energy.

Originally Posted by GMKing

if I go with a smaller tire than the converse is true. however, the engine techinically needs to work harder to move the taller tire than the smaller tire, so I'm wondering where does FE fall in? taller tire and greater FE or smaller?

14s > 15s
smaller tire > taller tire

(for FE purposes)

Originally Posted by GMKing

also, width of the tire, I can only imagine that going wider increases drag both from air resistance and creating a wider contact patch and therefor increases rolling resistance. but I might be wrong.

Air resistance isn't really a big deal with the tires, but ya the wider contact patch increases rolling resistance.

If you want all out FE a super light 15 and overinflate some high-mileage tires. Personally I'm happy with 30+ mpg and am willing to sacrifice mpg for stability on the road and the ability to maneuver out of potentially deadly situations.

[ozmdd]

If you really want to up your FE, tire-wise, pick up some OEM Prius wheels/tires, or even better (if the bolt pattern matches, which I think it does), get some of the 1st gen Honda Insight wheels, and try to locate the original-type tires they put on those. They were especially light and low-rolling resistance.

[ozmdd]

Good link for low-resistance tires:

http://ecomodder.com/forum/showthrea...ling-2813.html

[GMKing]

Originally Posted by ozmdd

Good link for low-resistance tires:

http://ecomodder.com/forum/showthrea...ling-2813.html

i've seen that, but thanks for posting it again, it'll make it easier to find later. i'm sure to pick something off that list, however it's deciding the sizes that is making it difficult for me.

while I appreciate supmet's response I no longer remember which is the greater than or lessor than symbol,

as well as from the measurements posted on the link given I can find no discernible link between width of tire and increased rolling resistance.

[rningonfumes]

Originally Posted by GMKing

while I appreciate supmet's response I no longer remember which is the greater than or lessor than symbol,

LOL...the alligator Likes to eat the bigger number. 6>5 or 6<8

[YarisOwnersDad]

Do you know why 6 is afraid of 7? Because 7 8 9 and 10.