Does it seem to make a difference on which size will help get better gas mileage?

 

Less rotational weight = better performance in every aspect except possibly strength.

For the same wheel design, 18" is lighter than 20" wheels. The difference in wights between designs varies a lot, though.

Oh, smaller overall diameter tires will get better FE than larger ones. P rated better than LT tires.

 

That makes sense for sure but I want the 20's dang it.... lol. Does anyone have any figures on how much different the mileage would be.... sure it couldn't be alot or could it.

 

You need to measure how tall the tire is or roll out. Go with a lower profile tire on the 20's and you can end up with the same roll out as the 18's.

 

+ 1
And also,,the wider you go the heaver they will be = less mileage.

Phil

 

I will be getting a 2008 FX4 with the factory 20's.

 

Looking @ Tirerack for aftermarket wheels, those that are offered in both 18" and 20" for the same design vary from 3 to 7 pound delta. The lightest 18" weighs 24# and the heaviest 20" wheel weighs 43#. That is significant!

I really have not heard people complain about the OEM 20's and FE. If I were in the market for a new truck, I'd get the 20" wheels. The proportions looks the best to me on the new trucks.

 

While the factory 20's do look great, they do have quite an impact on MPG's.

 

Towing ability & power off the line also!............

 

I think in the simplest of terms it does come down to the weight of the wheel. I know size matters, but generally speaking, the larger wheel weighs more, and the larger tire weighs more.

Is there any way to find out which Ford factory OEM rim weighs in the least? Which Ford OEM wheel and tire weighs the least?

I've looked at sizes of Ford OEM tires, and the 275/55/20 sizes in the smallest with a circumference of 93.4, and second the 235/70/17 at 94.1. I'll agree with Phil that the low profile 275/55/20 is probably heavier.

On the large side, the biggest goes not to the 20 inch but to the 255/70/18 with a circumference of 100.7, second is the 275/55/20 at 100.2. I would say that is why the 18 and 20 are in the same towing category.

I'm interested because I run the 20's on my truck, and wonder what they are costing me in fuel. They look great I know, but I like to drive too.

 

Curious what's the diff in total wheel/tire diameter between the OEM 18's and 20"s? Wouldn't the 20's be a lower profile tire which should weigh less than the "air baloon" tires on the OEM 18" rims? Might not be as large of a diff as one might think?

Also, I'm looking for a set of the OEM 20" take offs if anyone here wants to sell a set - PM me - I'd even throw in my OEM 18's (Lariat) wheels so YOU can get better mpg

 

• 235/70/17 - 94.1
• 255/70/17 - 97.6
• 255/65/17 - 94.4
• 265/70/17 - 99.3
• 275/60/17 - 94.2
• 255/70/18 - 100.7
• 275/65/18 - 100.8 (Spare for stock 20's)
• 275/45/20 - 93.4
• 275/55/20 - 100.2

 

The spare for 20s is an 18" rim with a tire that is close in size to the 20s. I have not weighed any wheels and tires, but I would expect that the 20s replace rubber with metal, and the metal adds more weight than was lost in rubber. Though close in size, the 18s and 20s would be close in weight, with the 20 weighing in a few pounds heavier.

Now, what weighs more, a steel wheel, or an aluminum wheel? Is the 235/70/17 on a steel chrome wheel the lightest tire? I think I like the 255/65/17 on an aluminum wheel, but would still be inclined to keep my 20s.

Do you think we can get enough people to take a wheel off and weigh it? Even then, how would we keep track of each rim? How much weight does a tire lose as it wears out?

 

Correct. Especially with 3.55 gears.

But I like the ride better with my 20's than my 17's on my 05.

 

I went from 17s with 265 70s to 305/50/20s and lost about 1 1/2 mpg.