Does size of tires effect MPG?
 

I believe the 2008-2009 Ford Escape Hybrids come with 17 inch wheels right, but what if I were to put 18 inch rims on?

Could that actually add MPG since an extra inch of tire would cover more ground? Has anyone added a bigger tire and what were the results?

super

Re: Does size of tires effect MPG?
 

Your thoughts are in the right arena, however the sidewall height of an 18" tire is usually lower, making the overall circumference about the same as a 16" or 17" tire wheel combination.

In order to accomplish what you desire, you can replace your 16" tires with bigger 16"tires - with an inch or two of additional circumference - ie. taller sidewall.

Most (perhaps all?) FEH's come with 235/70-16" tires. 235 represents the millimeters across the width of the tire. 70 means that the heigth of the tire (rim to tread) is 70% of the tire width, and the 16" represents the rim diameter.

You could increase the circumference of the tire by installing 235/75-16 tires. There are limits on the size tire you can put on your vehicle however. If you go too big, you may rub the inner fender or other suspension/steering components.

Since the Ford engineers leave a little extra room (assuming some customers will install slightly larger snow tires), I would guess another 3/4 inch in diameter (2 1/2" in circumference) would be close to the upper safe size limit. That would represent a 3% "overdrive".

I doubt your fuel economy would improve by 3% since there are other factors involved, but you might pick up 2%. (Rembering that 100 miles on the odometer actually represents about 103 miles and 60 miles per hour is actually 62 miles per hour.)

Re: Does size of tires effect MPG?
 

First of all, the FEH come with 16" rims only and not sure, but I think it's the same for the MMH. The Michelin Latitude Tour tires are special made for Ford and the Escape and are light weight Low Roll Resistant (LRR). Most likely any change of tire size or brand will decrease your mileage, handling, increase stopping distance and be louder than the stock Michelins. In addition, the stock rims are special light weight rims with only one option from Ford, and that is the rim for the Limited FEH. The only way I know to increase mileage on the FEHL is to put the standard FEH rim and new Michelin tires on them. I'm so impressed with the Michelins on my '09 FEHL that I have replaced two stock LRR Eco-Plus tires on the front of my '05 FEH with them. This has improved everything and as soon as the rear Eco-Plus tires with 50,000 miles wear out or make to much noise, I'm adding the new Michelins for sure. These new Michelins were not available through Tire Kingdom or Goodyear, so I got them from Ford which retail for $179 each, but I get them wholesale for $159. Both my FEH's have the stock rims and tires for the spare. The Ford 17" Gas Escape Rim and tire will not fit where the donut spare is located.

After reading about information on tires and rims for the FEH, the lighter FEH rim with the lighter weight Michelins are the best possible combination for mileage. You can find the weights and more information in a tread I started a few months ago:
http://www.hybridcars.com/forums/tires-and-rims.html

GaryG

Re: Does size of tires effect MPG?
 

This is a copy of John Morton's signature:
he actually changed the size of his tires for his 2006 FEH. He claims very positive results (compared to stock ECO-Plus tires) in all areas but mileage.

Attachment 3348

18"x 8" OZ Canyon wheels/Bridgestone Dueler H/L Alenza (255/55R-18) tires.

This is a link to his site and photos:
http://www.pbase.com/jmorton10/inbox&page=all

Re: Does size of tires effect MPG?
 

Tire diameter for stock =16+(2*235*.7/25.4)=29.0"
John Morton's tires =18+(2*255*.55/25.4)=29.0"

If your #rotations/mile is off by too much, you'll get a MIL.

Re: Does size of tires effect MPG?
 

what is MIL? and who is John Morton, is he a member here or something?

oh yea, and I found some rims I like that are also 18X8 , how much do you think that will effect MPG?
A lot, or just a little?

thanks
super

Re: Does size of tires effect MPG?
 

what do you mean very positive results besides milage? what other positive results are there?

thanks
super

Re: Does size of tires effect MPG?
 

oh yea, did he state how many MPG he was getting on those 18 inch wheels?

Re: Does size of tires effect MPG?
 

Oh, I didn't realize you were looking at 18X8 wheels. Since 18X8 =144 and the sq.root of 144 is 12, you should expect a 12% increase in fuel economy.

I hope this helps, since I obviously wasted my time on my earlier post.

Re: Does size of tires effect MPG?
 

well I wanted to get his opinion since he is saying something completely OPPOSITE of you which is 18X8 wheels had a negative effect on that guys MPG.

EXCUUUUSE MEEEEEE for wanting to get another opinion

super