Acceleration and wheel size
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Senior Member
Joined: Apr 2003
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From: Charlottesville, VA
Acceleration and wheel size
Dumb question - why does wheel size affect the acceleration of a vehicle?
If someone switched out the stock 18" 295/45 rubber for 20" 305/40 tires which had the rolling circumference as the stock set-up, would acceleration be affected?
If someone switched out the stock 18" 295/45 rubber for 20" 305/40 tires which had the rolling circumference as the stock set-up, would acceleration be affected?
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Joined: Jan 2003
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From: DETROIT, (formerly Eaton County, Michigan)
besides the extra weight of a 20" rim over the stock 18" rim?
If it is the same diameter there should be little change caused by the size of the wheel?
However, Ride quality (lower profile tire) will be worse, and the average 20" rim weighs much more than the 18", thus more rotating mass, that may slow you down a little
If it is the same diameter there should be little change caused by the size of the wheel?
However, Ride quality (lower profile tire) will be worse, and the average 20" rim weighs much more than the 18", thus more rotating mass, that may slow you down a little
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aside from the weight issue as mentioned:
it's basically adjusting the overall gear your vehicle is in. Your engine turns, and then turns the tranny in whichever gear its in, which turns the axle and differential (fixed gear ratio 3.73 most likely) and then turns your tire. Best to look at it in extremes. Imagine your tire was the size of a dinner plate. Assuming traction was not an issue, you would blow up off the line in a second because you can turn that can really fast but you won't go too far because you'll be in 4th gear at 5000 rpm in 20 feet. Then the reverse, imagine the tires were 3 feet high. Your vehicle would have a really high 1st gear effectively so it would be difficult to accelerate quickly. With tires that high it would be like starting off in 2nd gear.
it's basically adjusting the overall gear your vehicle is in. Your engine turns, and then turns the tranny in whichever gear its in, which turns the axle and differential (fixed gear ratio 3.73 most likely) and then turns your tire. Best to look at it in extremes. Imagine your tire was the size of a dinner plate. Assuming traction was not an issue, you would blow up off the line in a second because you can turn that can really fast but you won't go too far because you'll be in 4th gear at 5000 rpm in 20 feet. Then the reverse, imagine the tires were 3 feet high. Your vehicle would have a really high 1st gear effectively so it would be difficult to accelerate quickly. With tires that high it would be like starting off in 2nd gear.
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oh and for your application
original diamter: 28.45 in
new diamter: 29.60 in
if your a 01 + your effective rear end gearing changes from
3.73 to 3.58
if your 99-00 your effective rear end gearing changes from
3.55 to 3.41
Thats what i got.
You'll be at 57 mph when you are actually going 60.
original diamter: 28.45 in
new diamter: 29.60 in
if your a 01 + your effective rear end gearing changes from
3.73 to 3.58
if your 99-00 your effective rear end gearing changes from
3.55 to 3.41
Thats what i got.
You'll be at 57 mph when you are actually going 60.
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Joined: May 2002
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From: The People's Republic of Los Angeles
WHERE the weight is also important.
Assume a 100 lb wheel with almost all of the weight on the hub. It could accelerate faster than a 50 lb wheel with all of its weight on the rim.
The farther away that the weight is from the rotating axis, the more it will resist being moved -- torque is foot pounds (or Newton meters if you are in some pansy-*** part of the world).
But to answer your precise hypothetical, IFF the wheel/tire combo is the same weight, AND the weight is distributed the same along the radius of the wheel/tire, AND the combo is the same OD, there would not be a difference.
And replacing the stock 35 lb 18's with 20 lb 20's could actually result in quicker acceleration.
Assume a 100 lb wheel with almost all of the weight on the hub. It could accelerate faster than a 50 lb wheel with all of its weight on the rim.
The farther away that the weight is from the rotating axis, the more it will resist being moved -- torque is foot pounds (or Newton meters if you are in some pansy-*** part of the world).
But to answer your precise hypothetical, IFF the wheel/tire combo is the same weight, AND the weight is distributed the same along the radius of the wheel/tire, AND the combo is the same OD, there would not be a difference.
And replacing the stock 35 lb 18's with 20 lb 20's could actually result in quicker acceleration.
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From: Houston, tx
I replaced the stock 48lb wheels on my HD truck with 29lb forged wheels. Same size tires... It felt like bolting on 20-30HP at the rear wheels. NOTICEABLE difference. If you are going to go to the time and expense to change your wheels and tires, look for lightweight while you are at it.
I was also surprised to see a big difference from tire to tire in terms of overall weight. Since they are the outermost part of the combo, you might email the mfr of 2 or 3 of your favorite tires and get a weight....
I was also surprised to see a big difference from tire to tire in terms of overall weight. Since they are the outermost part of the combo, you might email the mfr of 2 or 3 of your favorite tires and get a weight....
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From: Albuquerque, NM
Tm got it right. Think about it this way, when you accelerate the vehicle in a straight line, you are accelerating the wheels in rotation and in a straight line. Therefore a pound saved in rotating weight is worth 4 to 5 pounds (depending on where the majority of the weight is, hub or rim) of chassis weight. This means reducing 20 to 25 pounds of wheel/tire weight is like taking off 100 pounds on the body. So 4 pounds per wheel/tire combo will make your truck 1/10 second quicker in the quarter.
