I'm sad

neomagus00

Originally posted by mbdyer12
Not sure on the wear. They suck though. Dont buy the Pontenza RE92's ever. Ever ever. Well, unless you like doing donuts. In that case, its ok. (Side effects may include sliding into curbs, poles, ditches, ravines when snowing or raining heavily). Nothing has happened to me yet but the traction is lacking.

not sure where this came from, but... i run bfgoodrich t/a kd (their absolute totl street tire)... freakin amazing grip... i have a 200 wheel HP vehicle, front wheel drive, and on level ground i can floor it, and these things stick like glue... and this is when they're cold... heat em up to 100-150+, and it's like superglue, duct tape, and some other crazy **** all combined... good times...

decent wear, too, though i haven't had them for a terribly long time... as a note, DO NOT drive these in the winter, you will get yourself killed; they get harder than concrete, with as much traction, and move snow worse than my grandma... very very very bad idea... decent enough in rain, though, even though you should get the KDW if you're gonna do a ton of wet-weather stuff.

mbdyer12

Hmm. I'll look in to them. I'm planning on gettin some 17x7.5 rims in 3-4 months and I'll need some decent tires. Thanks for the info

Steve@3dai

KD's aren't too hot in the rain.

If you want something that is a good summer tire (aka, dry grip and no hydroplaning) look into the Kumho Ecsta MX and the Toyo T1-S. The Yokohoma ES100s are also a decent tire (a little loud).

I would go with the 17x8 that way you can get a 225/45/17 on there without a problem.

mbdyer12

The only problem with 17x8 is price. I'm poor now that I have this car. I love my car. Very much.

But yeah, I'd like 17x8's if I can find a good, affordable, and lightweight rim.

Steve@3dai

www.subydude.com

Rota wheels are great for the price!

kwade89

awesome car!

audiobliss

mbdyer12
Sweet ride!!! I would love to have one of those. All well...

You think PolkThug's ride is a 330i?!?! It is obviously an X5 or X3. :rolleyes:

Bummer with the crack, though; hope you can get it fixed cheap.


Steve@3dai
Awesome car!! Isn't that the Legend? It looks really sweet. How's the performance?

Steve@3dai

Originally posted by audiobliss

Steve@3dai
Awesome car!! Isn't that the Legend? It looks really sweet. How's the performance?

Nope, Legacy GT.

It's 250hp/250tq but they've been dynoing higher, so I think they underrated it a bit. It's got a nice comfortable suspension that doesn't do too bad in the turns, just have to be smooth with it.

neomagus00

mbdyer - why are you looking into 17 inch wheels? if it's for performance, you're going in the wrong direction. if for looks, then you've hit it on the head that you need light wheels.

Steve@3dai

Originally posted by neomagus00
mbdyer - why are you looking into 17 inch wheels? if it's for performance, you're going in the wrong direction. if for looks, then you've hit it on the head that you need light wheels.

17" wheels don't give performance benefits?

exalted512

Originally posted by neomagus00
mbdyer - why are you looking into 17 inch wheels? if it's for performance, you're going in the wrong direction.

what you talkin bout willis?

neomagus00

no, larger wheels do not give performance benefits. the costs and benefits are thus:

GOOD
-Allows bigger brakes (as we'll see, this is the ONLY reason to upsize your wheels)
-With the same radius tire, shortens the sidewall, increasing lateral stiffness (less flex in the tire around corners)

BAD
-More weight; this is the biggie. A pound of rotating mass - like that of a wheel - takes far more energy to accelerate than a pound of static mass (by a factor of between 1.5 and 2). This means that there's more stress on the suspension, the engine has to throw down more power for the same acceleration as a smaller wheel, and it takes more force to turn the spinning wheel, thus increasing cornering effort, and decreasing cornering smoothness.
-The smaller sidewall can unnecessarily increase ride harshness; in addition, the smaller sidewall increases the apparent fender gap, making a stock car look lifted (the rule of thumb to avoid this is to ensure that your sidwall is at least as tall as the gap between the top of the tire and the bottom of the fender above it); finally, the smaller sidewall increases the risk of denting your new wheels. Well, you say, just increase the size of the tire, too! The problem with this lies not only in the speedometer (it will display wildly inaccurate speeds), but with the transmission (automatics will shift at improper times) and fuel mixtures (the ECU takes into account the speed of the car in its calculations, and incorrect tire sizing will throw these off, causing at best a decrease in fuel efficiency and at worst detonation). Note that these effects don't often happen, but they can.

As noted, a beneficial effect of larger wheels is decreased bending of the sidewall in corners. Today's tires are quite advanced, and the difference in sidewall height makes a minimal difference in flex. If you're concerned, get a high performance tire that boasts sidewall reinforcement (such as the KD's steel inserts). Thus, the only benefit to larger wheels is the ability to use larger brakes. In my opinion - and here it's only an opinion - more effective use can be made of available space than most people realize. You can put larger calipers, better discs, and better pads (whatever better means for you, here) in the same space that the stock brakes are in.

Just a final note - there's a reason Formula One cars use 13" wheels...

P.S. This list may be incomplete, and is based upon my personal understanding of the subject, so anyone with more information is welcome to support or refute these arguments.

P.P.S. The "factor of 1.5 to 2" i referred to above is a combination of a little math, a little bicycling, and a little guessing. (For biking, all of the mass of a wheel is concentrated at the rim; the rule of thumb there is 4:1, or a reduction of 10 grams on the wheel is equivalent to a reduction of 40 grams elsewhere; a car wheel is both smaller and more evenly-distributed, thus the ratio goes down signifcantly... if you want an exact figure, go with 2:1; that is, removing four pounds from each wheel is like removing 4 pounds X 4 wheels X 2 ratio = 32 pounds from the interior of the car) It truly depends upon the wheel/tire combination. Suffice it to say that unless you're going from a really heavy tire and wheel combo to a very light, very well-designed wheel/tire combo, you're not going to gain any performance advantages. If you reduce the TOTAL unsprung weight (the weight of tires, wheels, and brakes) you will put less stress on the suspension. The factor to consider for acceleration, braking, and turning is rotational momentum/inertia. I cannot provide numbers for this, as they depend on the particular weight distribution of the wheel/tire system you've chosen.

exalted512

if you get good light 17s everything you just listed wont matter
yes, big **** heavy "bling bling" wheels will decrease performance
the reason formula 1 cars use smaller wheels is because they go through a lot and they have to be made very well to endure the heat from friction with the ground and brakes which uses heavier material--but your typical daily driver doesnt have to worry about this
-Cody

swerve

Wait so you guys are telling me that bigger wheels don't make you a gangsta??? Crap... i must have heard wrong then...

-adam

MacLeod

I thought you were supposed to have those tiny little "bearing buster" wheels. Ya know the 10" beauties that stuck out a foot and a half passed the fender. Now those were cool. :rolleyes:

I guess all those ganstas got tired of having to replace tie rods.

neomagus00

let's consider the forces involved:
a formula one car will weigh just under 2000 pounds at the starting line, and is capable of decelerating from 100 mph to 0 mph in the space of about 55 feet (quite extraordinary, no?). That's just over six g's deceleration, which puts force at about 52669.05 Newtons (I can send the maths to anyone that wants them). Assume that this is all on the front wheels, which as we'll see is a good assumption for purposes of comparison. Thus, each front wheel, assuming a rigid tire, has to hold about 26335 Newtons of force back.

Rinse and repeat for a standard car. The Lotus Elise - a light but sporty vechicle - will go from 60 - 0 in 105 ft. This gives 10198.64 N total, or 5099 per wheel, under the same assumptions as above.

Allow me to digress in order to explain why the assumptions are valid for the purposes of this analysis. A formula one car has more weight towards the rear than a Lotus Elise, but that weight shifts more towards the front during braking than does the Elise's. Thus, the center of mass for purposes of force analysis is approximately the same for both vehicles, and thus moving it forward to the front wheels is not an unreasonable simplification. The fact that I noted it was a rigid tire is valid along the same lines. An F1 tire is a great deal softer and more compliant - in this respect, at least - than a passenger tire. It, however, compresses under a greater force. The Elise tires are harder but compress less. Again, the compressions are (more roughly here than above) equal, and removing their influence is a valid simplification.

Back to the point - therefore, an F1 wheel must absorb 5.165 times the force of a standard passenger wheel. I would seem to have proved your point on the forces involved, cody, which was not my intention, but nonetheless it is a valid analysis and must remain. However, I would like to make two refutations to this. First, the quality of workmanship in an F1 wheel is far above and beyond the quality found in the vast majority of passenger wheels, even aftermarket. BBS makes the F1 wheels, and to get a comparable passenger wheel setup amounts to thousands of dollars; since you seem to be about price vs. benefit, perhaps those thousands could be better spent to improve the handling in better, more cost-effective ways? Second, an F1 wheel typically does not encounter things like potholes and road debris. In fact, these things are carefully controlled and removed from the tracks. A passenger wheel can be subjected to momentary forces much greater than that of an F1 wheel, and the forces to which they are subjected are over a much greater duration. Since a typical F1 race lasts under 500 miles, and a typical passenger wheel is expected to last for well over 100,000 miles, I would prefer to have a bit more cushioning provided by the sidewall.

MacLeod

E=MC2

exalted512

i highly doubt all the force is on the wheel...
some of the force is in the vehicle itself, some is on the suspension, some is on the tire and the air pressure in the tire
theres a lot more involved than just simple equations bud
we need John in here...
-Cody

neomagus00

yes, mac, excellent work!

cody - i assumed that the tire was rigid, and at full braking, the suspension on a car is so close to it's stops (if it hasn't hit them) that the force there can be safely neglected. or, if you prefer not to, simply take a set percentage out of each calculation to throw through the car, and you'll still find that the results are pretty good. you will certainly have stressed components, but for the purposes of me proving you right, this is pretty close.

and fyi, john's not the only one that knows math...

exalted512

wasnt his knowledge of math that i was referring too...it was his knowledge of racing in general
-Cody

neomagus00

oh, okay then

and fyi...

exalted512

Originally posted by MacLeod
E=MC2

E=mc^2, not mc2
:rolleyes:

Steve@3dai

Originally posted by neomagus00

-With the same radius tire, shortens the sidewall, increasing lateral stiffness (less flex in the tire around corners)

What about the ability to have a wider tire? More contact patch.

There's not many 16x8 wheels, but there are plenty of 17x8 wheels. 8" wide wheel will allow 225 to maybe a 235 width tire.

neomagus00

Excellent point. That would be an uncounterable advantage of a larger tire. The question I would then pose - and I think I already know the answer, but I'll ask anyways - is "Would this extra contact area make a difference?"... I'm inclined to believe that the difference would far outweigh the cost of a heavier wheel. My only criticism of it would be cost - a light enough wheel would be quite expensive, and outfitting it with large, wide, and sticky enough tires to make it worth your while would also become quite expensive. I am also personally concerned with the durability of the suspension.

You could certainly go with one of the few 16x8 wheels, however...

A final note: F1 wheels are indeed quite wide: 14 inches at the front and 16 at the back. Perhaps this is the reason they can afford to use a very small wheel... and they can clearly fit enough brake in there, as demonstrated.

A post-final note: At some point one must become concerned with the amount of tire being scrubbed around a turn... wider tires losing more rubber around a given radius turn (this is primarily why F1 tires last only about 70 miles, because they twist them so freaking hard in the turns). The point at which this becomes significant depends upon the driver (or, more relevantly, the purchaser of tires). And an idea: would not the tolerances for suspension adjustment become tighter when the tire becomes wider? Consider camber - say x degrees of negative camber has the outside edge of a 6" wide tire lifted 1/4" off the ground (obviously the car would be lifted and the suspension compressed to observe this). Then, if you put a mythical 12" tire on a new wheel, and keep it at x degrees of camber, you now have a much more significant 1/2" difference. I realize that the numbers involved are exaggerated, but the point remains valid. Just a thought.

Steve@3dai

Well, I'm just saying that your initial post was "17s don't have a performance advantage". It was a little vague, so we're just making you clarify

Yes, it's hard to justify the sheer cost involved into going to a bigger wheel. Depending on the buyer and what his/her needs are, depends on if they need to get a bigger wheel.

Well, I have to get 17" or above, my rotors are too big for 16" wheels :cool:

neomagus00

Haha... and that, my friends, was my original point .

mbdyer12

You ask if the width of the tire would affect it enough to make up for the weight? How bout the other way? Theres aftermarket rims that are 17x8 that might weigh 1lb more than their 16x8 counterparts. I know for a fact that some aftermarket rims, quality ones at least, weigh very little. One pound more of mass wont hardly affect anything. I know about that moment of inertia junk and I know the wider the radius, the <blah blah blah, slowly dies out>... so yeah.

Now as far as looks go, theres just something much more appealing about 17" rims. I chose 17" cause any bigger is pretty gaudy (if its not on a truck) in my opinion. Plus any smaller makes it look like it just has standard econobox tires or even worse, has a set hubcaps...


It all really comes down to looks. The extra weight isn't there. Any disadvantages, because they're so small, will be overridden by the ability to put larger rotors in and the extra width of the tire. We all know that for every bit we can wait to brake, the less advantage acceleration has. If you can brake less and take the turns faster, so that you keep that speed, then you lose that deficiency even further. Once again, the deficiencies of the 16 and of the 17 pretty much negate each other.


As far as being more prone to a bent rim and ride quietness...I'll just have to deal with those. I plan on sound dampening the whole thing anyways.

Steve@3dai

Originally posted by mbdyer12
I plan on sound dampening the whole thing anyways.

Now that's gonna add some weight

neomagus00

So it's decided, you're getting 17" wheels... cool! Enjoy!

mbdyer12

Now that's gonna add some weight

Haha, shush it.

Anyways, if you read the cardomain page that I have up, you'll see that I'm going to offset it, and more, with some performance mods.