Currently on 17s and would like to go up to 18” or 19“ wheels. But there are some nagging facts in the back of my mind that I’d like input on. Are all of the points below true?

1. Handling- With a larger tire, axle height rises thus raising the car's center of mass. In turn this changes the way the car was intended to handle.

2. Fuel efficiency- it takes less power to move a smaller tire. So the larger the wheel, the more power/fuel used to move the car.

3. Speed- So larger wheels clearly rotate more slowly. Thus you would loose a step or two when coming off the line. Meaning your 0 -60 time will suffer.

4. Braking- braking distance is sacrificed as it takes more power to stop that larger mass from rotating.

 

1. That all depends on the diameter of the tire. Same tire diameter on whatever height wheel will give the same alxe height.

2. It's not related to wheel diameter---again it is tire size that matters. You might find better fuel efficiency with a taller tire.

3. Again related to tire diameter; not wheel diameter.

4. If your car has ABS and a wider tire is placed on the car and it still will go to ABS, the stopping distance with threshold braking (just short of making ABS engage) should be shorter due to larger contact patches of the tires. It's not so much stopping the rotating mass that is the issue. It's stopping the unsprung mass of the car.

 

going to a larger diameter wheel doesn't necessarily increase the overall diameter of the tire. to get an idea of the difference between stock and the larger wheels, look at the tires you'll be getting (Tire Rack lists tons of specs, that's a good place to check). if you're going to be getting larger wheels, try to get some that are very light, and pay attention to tire weight as well. my answers are based on maintaining the stock tire diameter:

1 - the ride height won't change. the handling characteristics can change greatly, however that will be due mostly to the tire (tire type, width, sidewall stiffness, etc). the weight difference of the wheel/tire combo can also affect handling in regard to how quickly the car reacts to steering inputs.

2 - fuel efficiency will generally improve with reduced weight (especially rotational weight, like the wheel/tire combo). getting a lighter setup should improve your fuel efficiency.

3 - this again comes down to weight. a lighter-weight package will be easier to rotate and improve both acceleration and braking.

4 - same as above.

 

a simple solution to keep your oem settings is to go with a smaller side wall height tire. for example, if you had 18" stock rims with say 265 45 18 tires. and you want to go to a 19" rim go to a 265 35 or 30 19 tire and your diamater will not change. tirerack.com has a converter when changing rim sizes so you can see the exact measurement differences.

 

bigger wheels will make the car more bumpy also

 

I have hre 20" on my 997 and brabus 18" on my Mercedes. After installing the wheels with appropriate tires, both cars feel slower and less nimble. Bigger wheels do affect acceleration in my opinion.

 

If you want an exaggerated comparison, drive a jeep with stock axle gearing and brakes, and larger tires.

I've got 33s on my jeep (up from factory 30s), and even though my rims are still 15x8, the tires weigh so much more that I loose a lot of power and braking performance.

It's not a sportscar, and I don't drive it like one, but it would be nice to have better brakes sometimes! For now I just leave 10-15 car lengths on the highway

Unsprung weight is the devil for any sort of performance driving.

 

Its a proven fact that even if you go with a larger diameter wheel that is the same weight as a smaller diameter wheel you will decrease power transfer, and sacrifice braking. The farther out you move the mass the more your power source, and or braking source have to work to either deliver power/torque, and braking force required to move said mass.

 

Who cares? Larger wheels with a thin tires are fly. Unless you are a real racer and need every bit of weight reduction you can get, I wouldn't sweat it.

 

FLY? Yeah boy, throw some D's on that whip yo! Chrome Dubs FTW

 

Thin tires as in low profile tires is what I am assuming your saying? Anyways its wise to stick with the stock diameter since the manufacture designed the suspension geometry specifically for that diameter. If you went bigger you need to redo your suspension geometry. My advice to you would be get some new sporty tires with lighter rims...You could go 'fly' and get some large rims like 22"s with some uber low profile rubber and wind up on the side of the road from driving over a pot hole. IMO.

 

I have been riding skinny tires since the lowrider minitruck days of the late '80s, and despite the hazards posed by potholes, I will always love the thin look. I have adjusted my driving habits over the years to ensure that I don't rip off front ends on my lowered vehicles and destroy rims driving over potholes. To me, it's a lifestyle choice. I do not like the giant wheels, but on sports cars, I feel that a plus sized wheel and tire combo with the thin tires looks best.

 

I understand your life style choice, but here in Chicago, the pot hole capital of the world, regretfully I inform you that thin profile tires serve no benefit on the street and you look like a tool trying to avoid every single pot hole.

 

What the hell do you mean by decrease power transfer?

A taller wheel/tire combo that weighs the same may have a higher moment of inertia, or may not. Depends on how the weight is distributed on the wheel and tire. A taller tire in general will change the overall gearing for the car. Sure first gear won't have quiet the same 5mph roll acceleration, but you will hit a higher speed before shifting. If you really care about track performance then you may want taller gearing anyways. It will depend on the type of tracks/autocross you do. Nothing about power transfer there

For braking yeah you will need slightly higher torque from the brakes to achieve the same deceleration. (The "power" will be the same, some physics stuff like conservation of energy etc) If you brakes cannot supply a slightly higher torque value then sure worry about this, but if you are cooking your brakes already, you should look at upgrading the pads/fluid/rotors anyways. This is just not a concern.

 

So your saying if you want different gear ratio's, and dont care about "slightly less" braking performance then go nuts with bigger wheels. And it would be very rare that a taller wheel would not move more mass outside its center point, esp since most of that weight will come from the tires.

And at any speed the change in ratio you brought up would suggest a difference in torque transfer required by the engine/drive train to turn the rotational mass, and or, for the brakes to slow down again. You cant talk a change in ratio and then say "nothing about power transfer". Any way you look at it, it has the potential to decrease performance all in the name of looking like a "Baller".