How much does tire and wheel weight effect MPG?

[ATaylorRacing]

I originally posted to this thread on 8/13/08. Here is a thought for you guys about a case where both winter sets of studded snows and summer original rims and tires weigh the same and are of the same size on the wife's Prius. In the winter time...even though the outside temps are the same as other days we used the summer set...the rolling resistance of the studded snows is TERRIBLE! She always gets 50-54 all in town driving with the original tires but with the studded snows mounted on the same extra set of stock rims we drop down to only 44-46 all in town...the highway mpgs are also down by a solid 8-10 mpg! The tire pressures are also the same. This winter we had great usage of them due to all the snow and the year before they only came in handy once. My 95 Neon also looses about 10 mpg highway with the studded snows.

[cbaber]

There is another benefit of lightweight wheels that has not been discussed. It makes it easier to do brake work, do tire rotations, etc.

But seriously, there really isn't any reason to buy expensive lightweight wheels looking for gas savings. Most OEM wheels are decent enough. Don't go putting 24 inch DUBS on your ride though. You are better off making sure tire pressure is maxed out, all 4 wheels are aligned properly, and your tires are LRR. Also, notice how car companies have switched their priority from weight to aero over the years. Think of the civic VX and HX with their lightweight wheels in the 90's. Then you have the Insight's and Civic Hybrids with more aerodynamic wheels. I think that is a big clue, that wheel weight is not as important as the air resistance it creates.

[Xist]

Originally Posted by cbaber

Think of the civic VX and HX with their lightweight wheels in the 90's. Then you have the Insight's and Civic Hybrids with more aerodynamic wheels. I think that is a big clue, that wheel weight is not as important as the air resistance it creates.

Permission to still like my HX wheels?

[cbaber]

Originally Posted by Xist

Permission to still like my HX wheels?

Of course! Unfortunantly when I bought my HX the owner put some aftemarket wheels on and didn't keep the originals. Luckily, I found a set with no curb rash. Only problem, someone painted them black. I plan on refinishing them to the factory look this summer, and installing them when I need new tires because my current tires are 15 inch not 14 inch like the HX.



If you have a car with lightweight wheels from the factory then great. The only reason I am spending money to get the factory lightweight wheels is because I am sort of restoring/maintaining the car as part of a larger goal to keep this baby on the road as long as possible. So if you like cars and it's sort of a passion like me, then you inevitably end up spending a lot more money than you need to on them. But it's fine because it's fun, or at least thats what I keep telling myself!

[Xist]

Well, I am ever-so-slowly working on smooth wheel covers, which will not cool as cool as the bare rims, but we will manage!

[Robin Lehnerd]

I would like to be able to easily get some cost effective fuel efficiency improvement out of lighter wheels...
Most math says forget about it.
Switching to lightweight allow wheels might save 20 lbs off the car, which is 0.5% of a 4000 lb car.
Mass isn't the biggest factor in fuel consumption even when you are talking about the total mass of the car.
Mass normally accounts for 10-30% of fuel consumption.

But I wanna have cool wheels...

Forget it.

Lighter wheels will make your car accelerate faster, brake faster (slightly) and boost fuel efficiency pretty close to zip... unless I'm missing something.

It's sad.

[Stubby79]

If you've ever stuck bigger, heavier wheels on an already under-powered vehicle, you would already have noted how much worse your acceleration becomes, and, along with it, the drop in fuel economy in the city. (Been there, done that, eventually learned my lesson)

[royanddoreen]

Those pedal bikes out now with the big fat tires are a good example of this. It’s like a noticeable diff when you don’ have a motor doing the work.

[California98Civic]

An interesting classic EM thread on this issue is http://ecomodder.com/forum/showthrea...tml#post239397

[mannydantyla]

Originally Posted by MetroMPG

The answer is there's no easy formula to figure it out. Also, the effect of just going to lighter wheels is probably fairly small (not saying it's not worth doing).

Weight reduction will have the biggest impact in city driving, obviously. As an example: GM just released "XFE" versions of two of its trucks, and lighter alloy wheels were part of the new mods package. They reduced mass elsewhere and added LRR tires too:

Result: 7% improvement (+1 mpg from 14 mpg) in the EPA city rating.

Source

locking rear diff huh... to help with the poor traction of the the LRR tires?