Anybody Notice?

[WRXgotit]

I'll be getting a new set of rims and tires before this winter and I was woundering if anybody noticed a diffrence in Torqe/HP when getting 17in-18in. Some have talked about this so I'm just woundering how many this has happened too .

[psb02wrx]

I'll be getting a new set of rims and tires before this winter and I was woundering if anybody noticed a diffrence in Torqe/HP when getting 17in-18in. Some have talked about this so I'm just woundering how many this has happened too .

i had 18s on my car for a few months. coming from the stock 16s, the only thing i noticed was the ride quality. with the wider, lower profile tires, the ride was a little harsher - or if you look at it the other way, there was more "road feel" with the larger wheels. as for hp / torque - i didn't notice much of a difference, if any. although i hadn't had my car that long when i put the wheels on there. i can't see it being that dramatic a difference.

[sisforsurfing]

You don't actually lose horsepower or torque from moving to a larger wheel. However, this is perceived by some people because, generally, the bigger the wheel the heavier. This increases unsprung weight, which makes every aspect of performance worse. This includes slowing acceleration, which makes for the perceived notion that larger wheels somehow take away horsepower.

[Integra96]

You don't actually lose horsepower or torque from moving to a larger wheel. However, this is perceived by some people because, generally, the bigger the wheel the heavier. This increases unsprung weight, which makes every aspect of performance worse. This includes slowing acceleration, which makes for the perceived notion that larger wheels somehow take away horsepower.

Incorrect. Heavier/larger wheels decrease horsepower.

[psychobooe]

You don't actually lose horsepower or torque from moving to a larger wheel. However, this is perceived by some people because, generally, the bigger the wheel the heavier. This increases unsprung weight, which makes every aspect of performance worse. This includes slowing acceleration, which makes for the perceived notion that larger wheels somehow take away horsepower.

I think he means that you don't necessarily lose horsepower when you get bigger wheels. If the 17/18in wheels and tires that you put on weigh the same as the 16in combo that you take off, then there will be no difference in unsprung weight and therefore no lose of power.

[Integra96]

I think he means that you don't necessarily lose horsepower when you get bigger wheels. If the 17/18in wheels and tires that you put on weigh the same as the 16in combo that you take off, then there will be no difference in unsprung weight and therefore no lose of power.

It's not only how much unsprung weight, it's where the unsprung weight is. 18" wheels that weigh the same as 16" wheels will most definitely slow you down - unless the weight is concentrated near the hub.

http://www.physics.uoguelph.ca/tutor...ro.angacc.html

[sisforsurfing]

It's not only how much unsprung weight, it's where the unsprung weight is. 18" wheels that weigh the same as 16" wheels will most definitely slow you down - unless the weight is concentrated near the hub.

http://www.physics.uoguelph.ca/tutor...ro.angacc.html

Understood, which is why I said heavier wheels decrease performance in both acceleration and deceleration.

Incorrect. Heavier/larger wheels decrease horsepower.

Please post some sort of evidence or at least a theory to prove your statement... given and I will glady edit my post as I don't like spreading misinformation
I would love to know how your wheel size and weight affects your engine making horsepower.

[Integra96]

Please post some sort of evidence or at least a theory to prove your statement... given and I will glady edit my post as I don't like spreading misinformation
I would love to know how your wheel size and weight affects your engine making horsepower.

Google: Newton + physics. There's a mountain of evidence for his theories.

Less power is "produced" by the wheels when they are heavier. The engine, of course, is the power source, but the wheels are the agent - i.e., the wheels perform the work on the road/dyno or vice versa. Just do a simple thought experiment. Dyno a car with 16" alloy wheels. Now dyno a car with 1600" wheels made of lead. Intuitively, what difference would you expect in the measured power?

[ynotajb]

Google: Newton + physics. There's a mountain of evidence for his theories.

Less power is "produced" by the wheels when they are heavier. The engine, of course, is the power source, but the wheels are the agent - i.e., the wheels perform the work on the road/dyno or vice versa. Just do a simple thought experiment. Dyno a car with 16" alloy wheels. Now dyno a car with 1600" wheels made of lead. Intuitively, what difference would you expect in the measured power?

+Juan million

exactly the way to think about it

[sisforsurfing]

The question was do bigger wheels take away horsepower, and I said no, they don't. Because they don't, because the engine still is making the same power. I also clearly said that bigger wheels decrease acceleration just like they decrease braking performance... perhaps the OP meant wheel horsepower, in which case I wouldn't have responded because I have no hands-on experience or knowledge about wheels causing parasitic loss, especially when it's +1 or 2 pounds per wheel.

Maybe I should've just posted "yeah, you'll notice slight differences in performance in general" and called it quits. Regardless, just a little misunderstanding I think

[Micah]

Sometimes I plan on buying lightweight 16" or possibly 17" wheels. Stocker weighs 16.5lbs each (at least this is what I seem to be finding using google).

BBS RG-F - 16x7 - 1 pc forged - offset +48 - 12.3lbs - $412 each
Kosei K-1 TS - 17x7 - gravity cast/shot peened - offset +50 - 13.7lbs - $199 each

I'd rather stay with the stock rims for now.

[RayfieldsWRX]

It was pretty clear what the OP was asking. No one really thinks that somehow the larger wheels are going to lower the hp output of the engine.

But yeah, put on some heavy wheels, and you will suffer the detriments associated with unsprung weight and rotational inertia.

[YBNormal07]

Larger wheels = typically heavier = < AWHP

Larger wheels do not equal < HP.

Taller wheels = lower gear ration = < AWT

Taller wheels do not equal < TQ.

Plain and simple.

The advent of dyno's measuring HP at the wheels seriously complicated everyone's lives!!

Crap CAI + BOV = < HP.

[idioteque]

I feel like pretending to contribute today (since I can't figure out what I will do about a catch can for oil)

Anyhow - as far as I can deduce from the Torque for Dummies example above... both Mass and Radius affect EFFECTIVE torque. Furthermore, the impact of Radius is actually squared making it even more of an impact. Now, measuring Torque is quite complicated and usually is not actually performed. Instead it is a derivative of the Horsepower output calculated using the RPMs (or some ****). So - in my opinion - radius is much more important than mass and I agree with whoever said it won't change the Engines torque - but I don't think anyone really cares about that - it does, however, change the effective Torque of "the system" thereby making the vehicle potentially quicker/slower in different situations... flame on!!

[RayfieldsWRX]

:shrug:
<crickets chirping>