Additional wheel/tire weight

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Nov 9, 2008
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Just how much does it matter? I know it's rotational so it's worse, but still.

I need to pull the wheels off and weigh, but I swear, on my Camry, I can tell that the wheels weigh more. I was not expecting that. It's not huge but I swear, it feels like braking is just a bit worse, and acceleration just a bit slower. I know the wheels weighed a few pounds more but did not expect this.

Had RT43 195/70R14's on steel rims, swapped in General Altimax 215/60R16 on steel rims. If the web is to be believed, this is only 5% speedo error, which I would not think dramatic. Ride is a bit worse, that I expected (low profile tires). Steering is a bit different, small adjustments are the same, but anything sudden results in the car suddenly turning, it's rather strange.

Now that I know they fit, I can take these wheels off. Apparently every pound matters in the wheels, who knew (other than every racer out there).
 
You also changed the wheel size - by alot. The size you have now is wider and taller so now you have more things than just weight that changed, wider wheels, taller wheels, 3 pounds per tire, and I'm assuming about 2-3 pounds per steel wheel. We'll just say 5 pounds per wheel/tire, so about 20 pounds added to the unsprung, rotational mass. That's a lot but the effects are worse with a low powered car. The taller tire will also make acceleration slower and the wider tire will increase friction.

EDIT: to add on, general rule of thumb is 4-5 pounds of unsprung weight to every 1 pound of sprung weight so I imagine the difference between rotational mass and sprung weight is even more.
 
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What matters is inertia, so how the weight is distributed. Even if these new wheels weighed the same as the old, chances would be the weight would be further from the centre and inertia increased. Think of it as driving on gyroscopes, you just fitted better gyroscopes.

Before you can slow the car down, you have to slow down each wheel (that comes first, the tyre deforms a bit so it doesn't break lock). If you doubled the inertia, that first part takes twice the effort now. The effect on the forward moving mass is limited, 20 pounds over 3500 isn't the end of the world.

The effect on damping is also significant. A camry corner unsprung weight will be in the 100 pound region, adding 5 pounds is quite a %-age increase. It affects the high frequency damping (wheel movements vs low speed damping - car body movements)
 
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