Wheels and MPG?

[corprin]

I have been putzing around the interwebz today trying to find solid information, but alas it IS the internet.

I am trying to figure out of there will be any increase in MPG by changing to a lighter weight wheel. All the information I am finding has changes in wheel size, tires, etc, which is NOT what I am doing. The vehicle, tire, alignment, paint color, driver, day of the month, etc will ALL remain the same; only the wheels will be changing.

Currently I am running a set of Cragar D-Windows in 15x7 which on the bathroom scale are 25.5lbs each. I am looking at a set of '99 TJ "Gamblers" which are 20lb each on the same scale. Taking this into consideration, will I actually see an increase in fuel economy by shaving this much weight off the rolling weight of the truck?

I know there are other things I can do for better fuel economy in my '99 XJ. I already have removed the mechanical fan, removed roof rack bars, cleaned up the airflow under the truck, Neon injectors, etc. I am just wondering if the WHEELS will do much.

 

[Co-opski]

It should but how much I don't know. Post up your results. I keep track of MPG and such over at Fuelly.

 

[shredwagon]

I was wondering the same - going from 16" to 17" wheels. Found this:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=29
If one could find the formula to calculate the increase/decrease in rolling resistance, you could calculate the resulting change in mpg in the same way Tirerack has done.
Try googling "rolling resistance mpg wheel weight"......

Edit: Doesn't make a big difference after-all - within reason..... or not as much as size of tire, inflation, aerodynamics, etc.

 

[Yellowkayak]

I went from 6 ply stell to 10 ply steel and lost 2 MPG...then I put on a topper and gained my 2 MPG back. I get between 19 and up to 23 MPG on the high way depending on if I get a head wind or a tail wind.

JJ

 

[red87]

If anything, the extra rotating weight will only make a noticeable difference in stop and go driving. Once you're up to speed, very little energy, comparably speaking, is needed to keep it there.

 

[corprin]

If anything, the extra rotating weight will only make a noticeable difference in stop and go driving. Once you're up to speed, very little energy, comparably speaking, is needed to keep it there.

... and this is good. I guess I should have actually mentioned the purpose of the vehicle.

it is 90% daily driver for my 3-6mi commute on city streets, or the 10mi on freeway with traffic at both ends. Most of the time though, it's a local runabout around town. Only a small amount is done off road, or over landing in it.

I think I may just give it a shot.

 

[red87]

Now I'm curious too. Post up your results when you get the new wheels?

 

[Buliwyf]

... and this is good. I guess I should have actually mentioned the purpose of the vehicle.

it is 90% daily driver for my 3-6mi commute on city streets, or the 10mi on freeway with traffic at both ends. Most of the time though, it's a local runabout around town. Only a small amount is done off road, or over landing in it.

I think I may just give it a shot.

Fuel mileage can't be optimized for such short jaunts. Any numbers you calculate on such short trips have so much error in them that they're allmost worthless. IME I can see repeatable results in highway use, but city driving can be very random.

Yes, lighter wheel will improve mileage. Easier to accelerate. And less weight for the tires to hold up. Don't forget lighter street tires. Those are a much better way to improve mileage.

If you only drive such short distances then don't waste your time. Lower gear ratio's, that are bad for mileage on the highway may have an effect on city driving. I notice better city mileage and worse highway milege with peppy gear sets. (4.30, 4.56, 4.88 etc.)

 

[BIGGUY]

You need to add in the cost of the new wheels too. As an example, does it make sense to go buy a $1000 set of wheels to save 20lbs and maybe gain 1/4mpg in gas mileage. You could buy a lot of extra fuel for the cost of the wheels. Just adding something else to think about.

 

[corprin]

Wheels are $400, and the ones I have been looking for, for a while. The current wheels are being sold to a friend at $200, so it helps a bit there. The XJ is driven on the highway during the summer months, and during hunting season as it's my lodge, so lower gears are not much of an option at this point.

Really, I am not expecting much at all out of the swap, but if I can see even a slight improvement from the reduction of rotating mass, I will be happier than just having my blingtastic wheels finally.

 

[scrubber3]

Wheels are $400, and the ones I have been looking for, for a while. The current wheels are being sold to a friend at $200, so it helps a bit there. The XJ is driven on the highway during the summer months, and during hunting season as it's my lodge, so lower gears are not much of an option at this point.

Really, I am not expecting much at all out of the swap, but if I can see even a slight improvement from the reduction of rotating mass, I will be happier than just having my blingtastic wheels finally.

To see a $200 difference in gas savings will take a very long time. You may never actually be able to justify the expense of the new wheels based on fuel savings. That said, if you like the wheels then I see no reason why you shouldn't get them.

 

[78Bronco]

To see a $200 difference in gas savings will take a very long time. You may never actually be able to justify the expense of the new wheels based on fuel savings. That said, if you like the wheels then I see no reason why you shouldn't get them.

$400 for new wheels. Does that include mounting and balancing?

 

[corprin]

$400 for new wheels. Does that include mounting and balancing?

That's another $60.

We will see where this one goes, the line I had on the wheels flaked out... and I am looking at a Gen I Montero to build my expo on

 

[reece146]

No difference.

On my rig I changed from a tire/wheel combo that weighed ~85 lbs per corner to a combo that weighs ~60 lbs. Made zero difference to fuel economy (tracked via fuelly).

My driving is usually ~85% hwy.

 

[wjeeper]

I have run both and steel wheels on several rigs in the past.........haven't noticed a change in MPG that's been measurable. I ran some borrowed DIY beadlock wheels on a 4cylinder YJ (heavy wheels!:Wow1: gutless engine:sombrero and then put back on my AL wheels. The MPG changed something like .5 MPG at the best, essentially negligible/ statistical fluke!

My two cents.........