Car Wheels


#1

Does having larger car rims mean that your car will have to use more horse Power to move?


#2

There are a lot of variables involved but as a general rule, this is true. More mass = more power to move = lower fuel economy.

However, it is possble to get larger diameter rims that weigh less - but lighter rims are also more susceptible to impact damage from potholes and other road surface irregularities.


#3

No. Horse power is what comes from the engine.

The power you feel in your car differs based on many factors.

The most important factors are:

[list]
More powerful engine (bigger is not always more powerful)
Lighter car (usually smaller)
Different gearing
[/list]

Most people who buy those large rims (ghetto rims) do so for looks. Some buy them because they provide better road feel. Everyone who gets them also gets a wheel/tyre combination that is more likely to be damaged by a pothole or other road hazard.

Another point to keep in mind is quality. While steel wheels all are generally of good quality and have a long life, those fancy alloy wheels of all sizes have wide differences in quality. Producing an alloy wheel as strong and as light or better as a steel wheel is very expensive so few are produced except for true racing wheels.

Larger rims are usually purchased for looks.


#4

www.carbibles.com has a great primer on wheels and tires. I recommend a visit.


#5

I’m guessing from your post you are asking if a low-profile tire with a larger internal-diameter rim (wheel) will require more horsepower to move. No. However, if you are considering putting a larger diameter tire on your car (outside diameter), the effect would be like changing the gear ratio in the transaxle/differential to a higher gear and it will seem like more power is needed.

If you’re just thinking of changing to low-profile tire with a larger diameter rim (wheel)then you should not notice any change in acceleration. Be aware, however, that the low-profile tires and large diameter rims, while attractive to some, have a number of serious disadvantages: (1) - Hitting a typical pothole can cause the rim to bottom out damaging the tire and the rim, (2) tires are very expensive and fugetaboutit if you have to buy a replacement rim.

Hope this helps.


#6

Great website.


#7

If the new wheels/tires have the same weight as the originals, and their center of mass is the same distance from the center of the axis, and the new tires have the same rolling resistance as the originals, then there will be no diffference in HP required to accelerate. These are usually not the circumstances when one changes from OEM steel wheels and their tires to aftermarket alloy wheels and their tires.

The aftermarket alloy wheels often weigh more than the OEM steels. Usually lower profile, wider tires are fitted. This all combines to produce a heavier wheel/tire, whose center of mass is farther out from the center of the axis. This means more HP is required to accelerate the wheels/tires and the vehicle. If you add in the higher rolling resistance of a wider tire, even more HP are used to get the car up to speed.

This topic is covered in the article Understanding Wheel Weight (p. 24, Honda/Acura Performance, HPBooks, copyright 1999.)