Fuel Consumption Question - Rims - Please look

tradertt · 03-16-03, 09:30

Hi, I have a question which I wonder any one with experience could help answer.

If .. IF I have 2 choices of Wheel Rims ..

1) A 15 inch rim that is heavy (8kg)
2) A 16 inch Rim that is light (6kg)

Which will have a higher fuel consumption? I know that it takes effort and of course more fuel to move a rim that is of bigger size ... but with its weight into effect ... will it be offset or even have better fuel consumption than the 15 inch one?

Thank you for this silly question.

4DSC · 03-17-03, 12:49

Quote:

Originally posted by tradertt
Thank you for this silly question.

This is a complicated question!

I thought about it for a short while, and came to the conclusion that I would still go for the lighter rim (16"). While it's true that most of the mass is now further away from the center of the wheel and thus harder to rotate, I think the general goal to reduce unsprung weight is more important. Lighter wheels help the car handle and ride better than heavier ones. I know this doesn't answer your question about fuel economy, but it's something else to consider. Maybe someone with a physics degree could help figure out the rotational mass thingy?

Don't forget to consider tire weight as well. I found out that in size 235/45-17 a Kumho Ecsta 712 tire tips the scales at 27.3 lbs, while a Toyo Proxes T1-S weighs only 23.8 lbs. This is an extreme example, but since you're increasing diameter and your wheel weights are so close already, it may make a difference.

tradertt · 03-17-03, 01:19

I have thought of it b4 .. because due to inertia the higher the unsprung weight the more it takes to get the car to move off which is directly related to your fuel consumption.

If there is a bigger rim diameter, the weight is spread out further thus more force is needed to make it start rolling ... but the weight could have a direct impact on it ...

Sometimes it makes me wonder if its worth while getting a RIM that is ultra light - OZ - or getting a heavier rim which is much cheaper. Wonder how much fuel will I save in the end ...

ANyone care to help

Lowejackson · 03-17-03, 10:41

Wonder how much fuel will I save in the end ...

Fuel savings – negligible

Handling changes – could be high, depending on the car, suspension setup etc

The issues you are talking about are interesting but in comparison to the mass of the car mass and engine efficiency, they are minor. In a race car setup, weight is critical for speed and handling but not for fuel consumption.

The biggest difference you can make is with the use of the accelerator peddle and driving style

Steven

tradertt · 03-17-03, 11:04

I have always heard people claim that they got heavy rims are it is affecting their fuel consumption

..

Quote:

Hi my comment is don't take taiwan rims if you can...very heavy ah...the end result is increase fuel consumption and sluggish for our car...me running on taiwan rims now..regret...that time should pay a bit more about 500 to get those light weight type...think in the long run and you will find the money well spent..Stamford got quite a range...go there see the model and then you can compare the prices elsewhere

tradertt · 03-17-03, 11:11

Quote:

Outside of size considerations, the weight of the rim deserves special mention. Heavier wheels means slower acceleration and larger wheel diameter usually means heavier weight. Though the information is hard to come by, comparing wheel weight is a good way to choose the right wheel. Chrome wheels tend to be significantly more expensive than their non-chromed versions of the same wheel.

Scottwax · 03-17-03, 11:40

Fuel savings won't be much provided the overall diameter of the wheels with the tires mounted are the same, but acceleration should improve a bit. I've seen dyno tests where heavier wheel/tire combos lagged 3-6 hp less on acceleration than lighter combinations. Once the vehicle is at a static speed, the hp is the same, which would lead me to believe that fuel consumption is also similar.

Motor Trend tested wheels on a Civic and some of the heavier set ups slowed the car by .4 in 0-60 and 1/4 mile runs, so go with the lighter set up.

tradertt · 03-17-03, 12:11

Have a look at my car .. this is my problem ...

Please advice. I forgot to check my tire specs but I believe its either

175/70R14
185/65R14

How can I fill up the gap ... what sort of rims can I change to ? Would it adversly affect my fuel consumption?

The wheels looks very small with a ugly gap between the tires and the body of the car ...

tradertt · 03-17-03, 12:13

See how small it looks when it compares to the whole car.

Jake11375 · 03-17-03, 02:45

I have a 95 honda civic and I had the same wheel gap problem like your car. My OEM wheel size is "14" with 185/60/14 tires. I plus sized to 16X7 rims with 205/45/16 tires. Now that it has been mentioned here I have noticed a drop in MPG but it is only about 1-2 mpg. Before, I would get about 37 mpg, now I get around 35. Believe me the trade is well worth the plus size as far as cosmetics. Perhaps an even greater concern would be ride comfort if you go too big. The bigger the rim the smaller the sidewall, thus less cushion. But, this can be countered with softer springs/struts and the right choice in tire. Good luck!

thomasfl · 03-17-03, 03:51

I agree that your car will look much better with bigger wheels, I didn't notice until you mentioned it though.

4DSC · 03-17-03, 06:41

I've been told that if you have a large wheel gap, moving up to larger diameter rims will only make it look worse because you have to maintain the same overall diameter and the increased empty/dead space in between the hub and the outer rim will make the gap look bigger, giving you a "4x4" look... Just my 2nd hand info.