DO YOU UNDERSTAND THE WORDS THAT IS COMIN' OUTA MY MOUTH?!!!

 

http://www.tirerack.com/tires/tests/plus1_grm.jsp

I guess the tirerack is wrong.

 

Either that or my physics degree is wrong. Fo-real-dough, wider tires will probably improve performance as far as grip, all I'm talking about is the energy required to turn dubs is usually higher than a smaller tire.

 

hurts straight line mainly, I bleeev, I like my nismo LMGT4's

good sidewall, tight corners

 

notice in the plus-sizing, the wheel width goes up along with the wheel diameter. i've been saying this the whole time: WIDER wheels/tires will help performance... TALLER wheels/tires (assuming width is the same) will hurt performance.

you didn't take the time to read my post, did you?

 

also, going from 14" to 17" wheels on a civic (like on the tirerack.com comparison) is one thing. going from 17" to 20" wheels on a z is a whole other story.

try putting 20"x7" wheels with matching tires instead of the 17"x7" on the civic and see how the lap times change. the civic makes less power so you'll see a more exaggerated difference than in a z.

what's the point of debating if you can't even correctly interpret your opponent's argument... or the facts, for that matter

 

Let's get back to the good stuff....

BlownZ, where are the pics!!!!!!!!!!!

 

Sorry for the hijack. I am tired of people confusing theory with real word testing. Next time I will continue this in the wheel forum. P.S did you notice how the 17"wheel (7 pounds heavier) was faster (more than a half second) than the 15" wheel with only a slightly larger contact area.

 

notice the civic had a suspension upgrade. with the wider tires and increased traction, the stiffer suspension would have exaggerated the gained advantage... maybe even enough to give faster lap times even with a heavier wheel/tire package.

remember, at a track, traction is everything... it determines how fast you can take turns and the turns are where you make or lose time.

 

one more thing... the 15" and 17" wheels are of a different line. the density might not be the same. with rotating mass, where the mass is located is even MORE important than how much mass there is. if a weight of 35 pounds is located toward the outside of a 15" wheel, it's going to take more energy to rotate than if a weight of 50 pounds is located very close to the center of a 20" wheel.

because these variables are not addressed, i would take the tire rack article with a grain of salt.

alddave, don't just blindly follow someone else's studies... use your head, analyze their findings, and determine how valid it is for yourself.

once again, assuming that wheel diameter is the ONLY variable, larger wheels will hurt performance.

 

alddave,

yet another thing... i think you're the one confusing theory with real world testing. with theory, you can analyze and evaluate a SINGLE variable and keep all other factors constant. however, that's impossible to do in the real world.

even slight wind changes can account for half a second over an entire lap at high speeds. force of drag is proportional to speed so the faster you go, the more force is wasted just to neutralize drag. and that's just one example of such variables. that's why in professional races, drivers are on the same track at the same time on the same day under the same conditions. you can't go at a different time and make accurate, legitimate comparisons. the tire rack obviously could not race the same civic on the track with different tire/wheel packages with different drivers at the same exact time.

so based on these "real world tests" you cannot conclude that bigger wheels do not hurt performance. and hey... guess what? theory would not be accepted and taught around the world (edited for typo) if it wasn't substantiated by "real world testing"

 

Great, like I said we can discuss this in the Wheel forum. I will also let the tirerack know that they do not know how to conduct comparison tests on wheels and tires.

 

Those saying performance is hurt by plus sizing wheels to say, 20's - consider this:

IF you change the wheels from 17's to 20's (for example), you can also maintain the same TOTAL DIAMETER. So say, the 17's had a total diameter of 24" (meaning the diameter of the Tire on the Rim). The 20's can then have a total diameter of 24" as well, by making sure the profile of the tire only adds 2 inches radius, 4 inches diameter, or total diameter.

Following so far?

So there, we have plus sized, and not changed the total diameter.

Next thing to consider:

Rotational mass. Say the 17" weighed in at 18lbs each. If the 20's are perfromace oriented, they also will weigh 18lbs or less. This will ensure the weight, and roational mass stays constant. Again, no performance is lost.

Next - what to do with all that clearance in the rims?

Answer: ADD BIG BRAKES. This will ADD PERFORMANCE.

Also, you can now lower the car even more (for racing of course), because if a tire blows, the added size of the rim will protect you from bottoming out on the track. This will add safety.

Lastly, the less sidewall flex there is, the more positive and precise the steering inputs will be. Yes, the ride will be more harsh. But this is ok, because on the racetrack, there are no speedbumps or potholes. And you wouldn't want 20's simply to ride on the street just for bling effect, would you??

[Proving that bigger rims actually do add performance, when done correctly and not just so you can roll like your idols in their rap videos.]