IcemanG17

So my stock S4 wheels are supposed to weight about 19lbs (front) and 21lbs (rear)...with stock S4 tires that means the total tire-wheel weight is about 174lbs.... (tire weights on Yoko ES100's spec from tirerack)

I was looking at aftermarket 18" wheels and they are all quite heavy...ranging from 23-29lbs (front) to 27-32lbs (rear)....with tires that would be between 202-224lbs...which is 28 or 50lbs more than stock....

How would this effect performance and handling? I know you want the lighest wheel-tire possible for best performance, but what kind of a difference would it make in street driving? I just don't like the idea of adding 50lbs to the wheels....

Thaddeus

I wouldn't. Unsprung weight (like wheels, tires, all the stuff not hung in the air by springs and shocks) is far more deleterious to handling than sprung weight. It's hard to get a wheel of reasonable durability and lower weight than the ones Porsche makes without dropping a bundle.

James-man

I thought the weight of the tire decreased with an increase of rim size. You must be looking at wider rears?

Good questions, I have no experience and thus no answers. Sorry.

mark kibort

the copy rims are heavy, plus they are larger than the stock stuff, as most go from 16" to 17" and also go wider. (more metal) however, strictly going from 17 to 18, doesnt weigh any more. Ive done this a bunch of times with same width wheels.
expensive wheels weigh 19lbs front and 20lbs rear (for 18 or 17 " 9.5 /11") cheapos, in 9" width, are in the 28lbs range. tires weight from 25 to 30lbs depending on the amount of steel belts.

forget about the "unsprung" weight. its only for extreme handling and bumpy race tracks, where that would be a noticable difference . as far as its effects on power, rolling weight has the effect at the wheels, as 1.4 to 2x as if it was in the car not rolling. this means, if your wheels and tires weight 50lbs total more, which is extreme, it would be like having 100lbs extra in the car, or a full tank of gas vs only a quarter tank. even that is pretty hard to tell the difference with. reality, is that you are talking about 5-8lbs per rim and thats 20-30lbs on the rolling mass, x 2, or like 60lbs in the car. the heavy rims are as strong, but they are heavy , but cost less. I loved my C2 rim copies, but it would be nicer to have genuine porsche due to the lighter weight.

Mk

slate blue

My Carrera lightweights ( 5 spoke) weigh 8 kgs front and 10 kgs rear, no tyres. They are a light strong wheel.

Cheers Greg

Jim bailey - 928 International

Perhaps 99% of the time you will not notice any difference.....the other 1% when you actually are driving the car as opposed to it being parked in the garage it will be hard to notice. Porsche made only minor changes in springs and shocks through the years as they changed wheel tire sizes !

IcemanG17

Greg
The 02 lightweights like you have are very light & strong...I wonder what the 997 18" 5 spokes weigh? For my purposes it probably doesn't matter, since I don't drive hard often enough to really matter.

Ispeed

Look at Earl Gillstrom: he has S4 flat wheels on the '91 GT. They arent pretty, but they're all business, those S4 wheels are really light and strong. Club sport wheels are a step up with no real increase in weight. We know 16" tires are cheap too.
Mine are cup wheels, they are only cast but supposed to be one of the lightest cast Porsche wheels. I hope I don't run into the wrong pot hole and bend one...
p.s. I did weigh my cup wheels with Kumhos and they were 44lbs rear and 42 lbs front. They were almost identical to my S4 flats with tires (can't remember the brand).

hacker-pschorr

FWIW:
The Carrera III 18" 997 wheels with Continental Sport 2 tires are 120lbs per side (when they were shipped, each box was 120lbs with one front, one back wheel / tire).

The car does not "feel" any slower, even with a 1" overall larger tire on all four corners. Actually the car tracks better with the steering feel. Not sure if this is the tire or going from an et52 to a et57 front offset.

tommytomaso

Iv seen a few issues on power loss from larger wheels that weigh the same,( 1-3hp loss ) seems to have to do with how far out the weight is carried, will also afect braking, but by very little...1'' taller tire is realy only 1/2 diferance to center axle...thats not too much of a dif, proble just a 2-3 mph dif at 60mph.. if you realy want to feel a diferance try changing a 27'' tire to a 35'' DAMM WERES MY HORSES!!!! >>time to change the gearing..lol

Dennis K

I can't feel that much difference between heavy & light wheels at the track. Handling and overall feeling is far more affected by the tire. Especially for street wheels, I value strength and aesthetics much more than weight. Even for track, strength is key. Who can afford to replace wheels or wheel halves all the time? Really cuts into the track budget.

mark kibort

you got to remember, the wheels are connected to the entire weight of the car. the effects, as i said , are equal to if the weight was sitting in the car, times up to 2. so, 50lbs in the car, you think you will feel this??? never.
and yes, the effects of the 50lbs could be equal to 5hp.
Now, thats running 5-6lbs heavier tires and wheels. going 1" larger or 2" larger diameter is a rounding error! not measureable. its a rear end gear change issue by near 4%. (corrected)
Hp required to move the slightly larger mass is sub 1hp at most all usable speeds. slightly more from a stand still to 1st gear speeds. Its rate-of-speed-change dependant. (rate of change of kinetic energy is equal to HP)

MK

FlyingDog

On our cars compared to stock tires that's 4-8%.

tommytomaso

MARK<I don't know why your telling me like i dont know somthing, 1-3 hp is little to nothing...its also just shy of a dif between a tune-up and no tune up. so your retelling me your stats in "MATH" terms like that make you more RIGHT!!??? MArk i like 90% of our posts...but im seeing you feel a need to SEEM right.... unnesasary. and by the way, thier are many who can tell by FEEL that thier car is not running right...and i bet the HP dif is just 5hp or less. so lets not quib the little suff.. truth is alota little things can make a dif.. and knowing at what point little is alot is the game....
a spinning mass of 50lbs...WILL NOT in the REAL world react just like 50lbs sitting beside you. if you argue that point WHAT the hell computer are you using.. try not to compare your RACE car to our unrace prep cars.. thier are ALot of small mods that your car has that will balance out things that would show up more prononced in a street car. ie: 5hp to the ground in a car thats only getting 190 to the ground is ALOT! not like in a car thats getting 300+ to the ground.

mark kibort

right! usually, stock tires are 24.5" and a 305x35x18 is 25.25" thats 3%. 8%? nah, i havent seen too many 26.5" tires around, but the 335x30 is near 25.5

but yes, its more than 1% that was a typo

thanks,

MK