There are numerous things that determine MPG. For example, sitting in your driveway with the engine running is achieving ZERO MPG, so in this case tire size is not an issue. Too high of a gear ratio can actually decrease MPG, and too low can do the same thing. When it comes to the best top gear ratio, you would have to factor in desired speed, in order to determine optimum MPG. Do you want to cruise at 60 mph, or 80 mph? Tire size (too big and too small) is another factor. Too big, and tire weight becomes a problem...too small then high spin speed becomes an issue, etc, etc. Yes, changing tire size is in essence changing gear ratio. Higher ratio is not always better, especially if you have multiple passengers, climbing hills, head winds, etc. Whether its better is hard to determine without actual testing. Driving conditions are always a compromise.

 

Higher MPG could be the result if...driving on flat terrain, no passengers, reasonable cruise speed, etc, etc. But I doubt that it would be much. I would be more interested in better ride quality and improvement in road noise.

 

tire size does NOT effect alignment

Lowering my car will not fill in the wheel well. There are still the sides (front and rear of tire)

Im lowered 2 inches, a half inch taller tire equals a quarter inch all around, not much of a difference, but a minor difference can make something look better.

It wont make it look goofy, you wont even notice such a small change in height

 

I doubt it would have much if any effect on mileage. The aerodynamics are what determine that on the highway along with the weight. The biggest benefit I see is it might ride a little bit better with more rubber.

 

I agree with others--taller does not necessarily mean better MPG. Even getting lighter tires seems to only have negligiable amount of MPG gains. I've tried 185/60/15's tire (Yoko AVID), which is about the same size as stock and bit lighter. Unfortunately, saw virtually no increase in MPG. Handling definitely suffered, though. I think I will go back to 195/55/15's and at least have some of the fun back.

If I were truly going for better MPG, I think I will go to light 14" rims paired with Mich Destiny/Defenders (185/65/14).

 

Actually lighter tires will work wonders for MPG, given the new tires have the same or reduced rolling resistance


a pound off the tire is similar to removing 4 pounds in rim weight. (this is a rough rule of thumb)


Grab something that weighs a few pounds, get on an office chair that spins, and compare spinning with teh weight against your chest and the weight held outstretched

You will notice the closer the weight is to you the easier and longer you spin.

Same idea of simply cutting outer weight from anything spinning.

 

I understand concept. But theory and real world application does not always translate directly. (Why do you think I bought the LRR tires to start with?)

 

I'm rolling on 195/65/15 25" diameter (1 inch larger)

my tires feel little bit lighter than the base tires with steelies.


smother ride, but almost bouncy lol i think i went too far. go with 1/2" inc in diameter


mpg is about 35

 

bigger diameter or heaver tires reduce mpg and acceleration. putting larger diameter tires will reduce gearing by the ratio of old vs new tires which is the equivalent of lower gear ratio..
generally speaking, bigger tires of both diameter and weight will work fair when there is little change in elevation and little acceleration and deceleration because the drop in engine rpm reduces mpg when only constant speeds are observed.