HP loss with bigger rims

[94CamaroZ28]

I was going to put 18x9.5 2000 Z06 rims on my '94 Z28. Would these bigger rims cause any major HP lose at the wheel compared to keeping the stock rims on, or would the better traction with wider wheels be worth the up-grade?

[89IROC&RS]

you dont loose hp through physicly taller rims. what you loose is gearing. if you take a car with 25in tires with 3.42 gears on it for instance, and then put 30in tires on it, it will accelerate like it would with the 25in tires and a 3.08 gear in it. (havent crunched the actual numbers here, just throwing out a general idea) so all you would have to do is put say 3.73 gears in it with the taller tires in order to regain normal acceleration. but hp would not change. so the added surface area for traction (oh god please please PLEASE dont let joseph see that i wrote that ) will be worth the upgrade. i myself am looking to put the 17in covette rims on my third gen. but with the 17s and the right tire, they match the original height of my stock wheel/tires. so i dont really have to worry about it. just have to use spacers is all.

[94CamaroZ28]

I did the same thing with my '86 Iroc. I put the spacers in the rear springs, but the problem I ran into on the front wheels is when I turn the wheel the tires rubbed the front of the fender.

[89IROC&RS]

the spacers im talking about are not on the springs...

http://www.thirdgenresource.com/inc/pdetail?v=1&pid=436

they bolt onto your hubs, and give enough clearance for the new wheels to fit right where the old ones did, cuz the overall dimentions are the same, but the backspacing is different, so the corvette rims dont stick out so far, but are closer in towards the engine by about 2.5 inches, these spacers move em back out where the stock tires would be. so with these, you shouldnt have a problem with the vette tires.

[Joseph1082]

Hey.. I saw what you wrote... Torque is Force*Distance right, ok. It is obviously a constant for your car. So you increase the distance from the center of the wheels to the edge, torque stays the same, the actual force to the ground goes down. So yes you need a something to increase the torque to make up for it, to keep the force at the same number w/ the new distance. Iroc you explination was fine... but since you mentioned it I had to do it. Didn't feel like crunching numbers though.

[z28 boy]

Iroc89, correct me if i am wrong but what u are saying is that smaller tires have an advantage right? Here for example take my car it has 3.23's and smaller than stock tires, does that mean that i have the advantage over another car with 3.23's and stock tires? Am i faster?

[z28 boy]

ok i thought it didn't post the first time

[Joseph1082]

You may or may not be "faster" but you will be applying a greater linear
Force to the ground, Torque(constant)=Force*distance... lower distance, force goes up. From your point of view, the "neck-slapping" effect of torque will be greater.
Come to think of it... it is a trade off, because now you may have more force, but less speed. The circumference of your tires is lower now, so at the same exact RPMs on the highway, the car with bigger tires will be covering more distance aka going faster you'd have to increase RPMs to maintain similar speed. You know what, smaller tires pretty much have the same effect as taller gearing. That is why to keep everythnig equal you'd need to adjust gearing to counter the adjustment in tires.

[drvngstorm05]

Originally Posted by Joseph1082

You may or may not be "faster" but you will be applying a greater linear
Force to the ground, Torque(constant)=Force*distance... lower distance, force goes up. From your point of view, the "neck-slapping" effect of torque will be greater.
Come to think of it... it is a trade off, because now you may have more force, but less speed. The circumference of your tires is lower now, so at the same exact RPMs on the highway, the car with bigger tires will be covering more distance aka going faster you'd have to increase RPMs to maintain similar speed. You know what, smaller tires pretty much have the same effect as taller gearing. That is why to keep everythnig equal you'd need to adjust gearing to counter the adjustment in tires.

physics lessons all over again lol...

[Joseph1082]

Sorry... Hey, I told everyone I will make a good physics/math teacher. Now you guys just have to put up with me.
I mean, I only feel I'm contributing to AF becasue the whole reason to rhyme here is for education, so if can help educate others and further the AF cause, y not, I owe considering all the stuff I've learn on here myself.

[z28 boy]

So let me ask do have an advantage at all off the line?

[Joseph1082]

Smaller tires, YES, going to smaller tires is the same as going from 3.08s to say 3.42 (rough estimate) I think Iroc already said this. So it will give you that better accelreration. Now on the highway your RPMs will be higher. It is the same as changing gears, so you have to weigh your options as if you were considering gears... like you might not want 4.10s even though they are faster because you'll burn through gears quicker. It's up to you.
Never really thought about this until now, hey, I might go to slightly smaller tires now, thanx.

[z28 boy]

yeah i calculated the difference in tires size and stuff and i got that with the smaller tire i am runing something like 3.34 gear ratio or something like that but i don't know the exact diameter of my tire so i am not sure if it is right but its better than my 3.23's.

[Joseph1082]

there ya go

[89IROC&RS]

bingo bango, yall already covered it.