armour845

There are plenty of kids on this forum you can discuss your bigwheels with, however; I am not one of them. We've all heard the expression, opinions are like a$$holes, it just seems like most of the comments I have seen you make on this forum your opinion seems to come from yours.

Not back to the adult conversation, I can understand the sidewall flex of the tire resulting in greater ET's at the track, so we can consider that portion of my thread solved. Now ratnacage, wouldn't the decrease in outer diameter increase the amount of torque to the ground, thus increasing horsepower. I not sure about the weight of the tires, I didn't weigh them.

Also sorry for the confusion, by increased traction I should have explained better, I meant to say cornering grip.

Moose if you look in my signature pic, you can see my daughters bike, you can come over and take it for a spin if ya like!

StowesStang

I dont have actual proof but I can tell you that I have always run a 20" when I can and I have run 20s on both of my 07s. Granted, my son's GT (with 17s) would whoop me every time but at the tree I do grip pretty good. Soooooo, to compensate for my big wheels, Im getting ready to replace my 3.55s with 3.73s, put on some headers and maybe some modest suspension and Id be willing to bet Id smoke his lil ***!!! lol Because Im into my pony look more then performance, Im willing sacrifice a bit of HP but I like I said, I can get that HP back with a few extra performance mods! Bottom line, Im sticking with my 20's and will work around the loss of HP, which to me, is not that big of a loss! There is alossthough, no doubt!

GTJUNKIE

Now that was funny my friend.LMFAO


Moose if you look in my signature pic, you can see my daughters bike, you can come over and take it for a spin if ya like!

ratnacage

It would be easy if your overall diameter and mass increased, but since we don't know for sure the final weight (mass)of the wheel and tire together, it's hard to say how everything works out in the numbers. Thinking about it more, if the rims weigh the same, and overall wheel/tire diameter decreased, then logic should say that the tires weigh less than stock, so if this is the case, then your rwhp should not have been hurt.

..but the simple answer to your question is yes, all else being equal, decreasing wheel/tire diameterwill generally increase torque to the ground.

An easy experiment to prove this is to take a broom stick and push a chair around - not pushing straight ahead, but as if you were standing in the center trying to push it in a circle around you. Try doing it using the full length of the stick, then try it using half the length. You'll notice it gets easier as the distance between you and the chair decreases. In other words in order to apply the same force at the point of contact with the chair, you must apply more force (torque) as the distance increases - this also shows that torque is lost between the point of origin (you) and the end of the radius (point of contact), so the longer the radius, the more torque is lost. Doing the same experiment with a heavier object proves basicaly the same thing; that is, as mass increases more force (torque) is required to move the object at the same speed.

RodeoFlyer

Go to Barnes and Noble and buy a book. I mean that sincerely. I'm not being a dick. Look for something by Herb Adams. He includes great diagragms and charts, and puts things in simple words to make it really easy to understand.

It is documented all over the place. The ONLY advantage you have is that yes, a taller tire increases traction, HOWEVER that rubber band of a sidewall doesn't flex much. Static weight, rotating mass - it's all against you. Believe it or not,if you had a 17" wheel and a 20" wheel and they both weighed exactly the same, the car would perform better with the smaller diameter wheel.

dirtydeedsinc

Not only do you have to consider the overall mass of the wheels & tires, but where it is in relation to the center of the tire. Like ratnacage's example, the chair weighs the same but the radius where it is at changes. If the overall diameter of the tires doesn't change but the rims do, you are putting that mass further from the center and require more torque to move it which in turn shows as a decrease in HP. It takes more power to do the same amount of work. Now, by decreasing the thickness of the sidewall to get close to the same overall diameter, you will also decrease sidewall flex. Then again, with more of a radius on the rim, you have more leverage to induce sidewall flex.

Easiest answer, it depends on the style of rims you have, overall diameter of your tire and what the original overall diameter was as to whether or not you will lose HP or stay about the same. A solid rim will require more HP than one with holes. What you have to remember is you are sending the same amount of HP to the tires but it is requiring more to turn them with more mass further from center.

So is this confusing enough yet?

Perdi

Ummm, good thread...i was interested in this cause of the 18/20 debate...

In Moose's defense, he was not being derogatory, he was simply trying to make a comparision... You guys need a MIDOL or something?

armour845

I appreciate the all the help with understanding the difference from a scientific standpoint. I have done plenty of research with the search function on this forum, and the overall feel I got after about an hour of clicking through opinion after opinion is that there are two schools of thought. The first school of thought "20's don't belong on the Mustang, and should be avoided at all cost." A lot of people link the 20" wheelto rappers and punks and wouldn't put them on their car, even if they liked the way they looked.
The second school of thought is, and this is where I am on this issue. The wheels are strictly an appearance mod, and unless the wheels bring the car to a crawl, the performance and or traction loss is worth it. I really don't thing it makes that much difference for redlight to redlight street dashes as long as the car has decent tires installed. Obviously thewheels or any other appearance mod will not show any benefits at the track. The street is about looks and performance.At the track all that matters is how fast you cross the finish line. Lucky for me, I can enjoy the best of both worlds. The 17" Bullets are like the plague, I can't sell them for any more than $300.So I'll put some drag radials on them for the times I really want to tear up the pavement or track.
As for the big wheel comment, it's comments like these that clutter many of the forums on the internet with useless information.

Perdi

I think ya'll missed the point regarding the Big Wheel comment.... I understood what he was trying to convey... it was not a worthelss post...nor a waste of space... Think about it.......

howarmat

I agree....he wasnt being an *** with his comment at all, unlike the comments he got back from it. He is right...do you see 20" drag radials....no....there are good reasons for this. Its not like you cant make a 20 wheel weigh just like a 16-17. But you still dont see them. The comment wasnt scienctific but it sums up the thread quite well.

If 20s didnt hurt you on the strip then companies would probably be making them.

Its not "cluttering up the board with useless info"