Do bigger wheels on a car affect its mileage, speed, or acceleration?

Question

Because a larger wheel at the same RPM would theoretically travel farther than a smaller wheel, unless engine the bigger wheel makes the engine work more. Does anyone have a better explanation or concrete evidence?

When I said wheels, I meant the diameter to the edge of the tire.

I guess my word for "wheels" are rims. Sorry for the misunderstanding.

Answer 1

Larger diameter tires have the exact same effect as a taller rear-end gear ratio or an overdrive. It allows the engine to run at lower RPM in order to maintain the same speed. Lower RPM can mean less fuel consumption. Up to a point, you can get better mileage. The whole idea of a transmission in the first place is to keep the engine operating in its own optimal RPM power band. But at some point after increasing the tire diameter, the engine is operating below its optimum power band, which is the range of RPM where it is producing the most power. The result is that it will bog down and you will either need to "mash the pedal to the floor" and kill your mileage, or you won't even be able to accelerate. The same thing happens when you try to start your manual transmission car moving in 5th gear, or you try to get your mountain bike moving in the highest gear. Ain't gonna happen, because your car makes very little power at or just above idle speed. In fact, you can prove all this to yourself with your own car or bike. Just remember this physics absolute: Increasing the tire diameter has the exact same effect as shifting into a higher gear.

Answer 2

I'm not sure you're really grasping this. The diameter of the tires (not wheels) determines how far you go. Wheels have nothing to do with it. Larger diameter tires (not wheels) will result in the engine turning slower at the same speed of travel. There's no reason to think you'd just automatically drive faster if your wheels were bigger. That's not what you'd really do. You'd really drive the same, with slower engine speed.

Obviously, acceleration will be slower. Nothing you can do about that. If anybody makes an argument to the contrary, don't listen. Gas mileage can go either way. If a car is really well geared to begin with, larger diameter tires will make the mileage worse. You wouldn't think so, but it does.

Answer 3

iff all things remain the same, and you put a larger diameter wheel on your car, it will likely slow it down (unless the new rim is much much lighter than the smaller rim....this is the case with magnesium alloy wheels)

if your engine is spinning at 5000 rpm in 5th gear, then the larger wheel will be spinning slower than the smaller whell....and if they weigh exactly the same (hard to do) then it likely will have zero impact on how fast your car is actually travelling.

only upsize your wheel rims if you are going with a light-weight alloy.

doing it for style alone will wreck your accelleration and mileage.

Answer 4

its the outside diameter that makes a difference. if you keep the same o.d. then the difference is negligible. the thinner sidewall will give you a little better handling but will expose the rim to more abuse if you have crappy roads with potholes. increasing the outside diameter of the tire will lower the rpm your engine runs at but will increase wind drag. decreasing the o.d. will give you more mechanical advantage so you get better acceleration but will make you revv higher to be at the same speed, so mileage is reduced. the o.d. of the factory tire is the best average.

Answer 5

The current fad is for big shiny wheels with skinny rubber band tires. You need to measure the outside diameter of the tires to determine if they will make a difference. With bigger wheels the speedometer will read lower than the actual speed.

Answer 6

I don't think it does. I think the only think that affect mileage, speed, or acceleration probably is the engine.

Answer 7

Bigger tires will throw your speedometer.eg if your speedo reads 60mph, you are actually going 65-70mph

Answer 8

It will decrease your fuel economy.