Why 20" wheels

[rbowman]

It *may* decrease the unsprung weight. Some of the 20" wheels marketed for the bling factor may be heavier than a smaller wheel/tire combination with the same rolling diameter.

[Diesel]

That depends on the paint being used. Some paints have additional heat dissipation properties which can extend the life of the caliper, rotor, and brake pads. As, over heated pads aren't providing much if any stopping ability; and depending on the amount of excessive heat and resulting damage, they may not provide much or any stopping ability when they cool down to normal temps, either. Just ask a trucker who's ever had the misfortune of heating his brakes up too much.

I suspect you know very little about race cars of various kinds based on what you've written...I'm no pro racer myself, but, I do have a track truck, and know professionals who are. It's not all about looks for them. as Gordon pointed out, previously.

[rbowman]

And the rim portion has a greater circumference and weighs more than a smaller diameter wheel, to say nothing of having a greater rotational inertia. Some 20" rim/tire combinations may be lighter and have less rotational inertial than 16", some may not. The air volume between the spokes doesn't mean shit. Got it now?

[rbowman]

What do you think the cost difference between the track setup and Ricky Racer's TireRama bling package might be?

[rbowman]

If you're driving at 80 mph, the legal speed on the interstate in this state, how far away can Bambi be when you do 80 to 0 if you don't want to scrape the hood?

Of course, 20" rims may or may not decrease the stopping distance.

[rbowman]

Thanks. I couldn't find a good weight comparison but that article certainly shoots down Gordon's 'more air between the spokes' theory.In fact the steel 15" wheels are the way to go for performance.

There is a parallel comparison with putting aftermarket exhaust systems on a Harley. Many of them actually decrease horsepower and torque. But they're kewler and louder :)

[rbowman]

Do you have a 'in specific' counter reference that doesn't involve very expensive track components?

[rbowman]

Put a chalk mark on the tire's sidewall the lowest point, continuing the mark down on the pavement. Drive forward until the chalk mark is at the lowest point and again mark the pavement. Measure the distance between the two marks on the pavement and do the math. Voila, the rolling radius.

[clare]

That is assuming spokes, and assuming the spokes are not larger Also the larger the rim the more aluminum in the rim - and aluminum weighs more than sidewalls and air.

He wants smaller rims with the same radius if he wants a good ride. - but you are right below - - -

[clare]

And now all the annabees have to have big wheels with low profile tires to "look good". It's ALL styling on the average street car.

[clare]

Only need more braking power if the tires can hold it - otherwise the ABS just shuts them down anyway.

That said, I DID put bigger brakes on my Ranger - it really needed them BECAUSE I put on bigger wheels. So which came first - the chicken or the egg?? With the little 14 inch wheels and tires the 10.25 nch rotors were plenty adequate. With the big boots on the 16 inch rims, the extra leverage made the 10.25s imadequate, and the 11s made a big difference. Same pads and calipers, just applying the braking farther from the axle.

[clare]

Someone had totally butchered your first Pontiac, so of course you had trouble with it. You can be virtually guaranteed NONE of the problems existed when the car was new - all were caused by someone who didn't know what they were doing futzing with it.

[clare]

Depends on the car, but whatever sized rim allows a 70 series tire to be the right rolling diameter is about as good as it gets. Not only the right rolling diameter, but fits the wheelwell to make it look decent, and llows full suspension and steering movement without hitting body or frame. Different for each vehicle.

16 inchers fit the bill for the majority of todays cars.

[clare]

GENERALLY speaking, the bigger the rim the more it weighs. Same with the tire. The sidewalls are the lightest part of the tire.

[clare]

But Mikey isn't looking for a brand new one - and if he is that 4 cyl eco-boost will curl his hair - - -

[clare]

snip.

Low profile means they are a smaller percentage of tread width in sidewall hight. A 78 series tire has a profile 70% as high as the width of the tread. A 70 is only 70% - a 65 65%, a 60 60%, all the way down ro a 40 at 40%. So a 205 78 has a sidewall hight of about 160mm, a 70 about 144, a 60 about 123, and a 40 only 82. A 255 78 is 199mm, and a 255 40nis only 102mm.

On the big buick it was more than just tires that made the ride, but they definitely contributed.

The Picanto is a "souped up golf cart" - just a bit too big to meet the Japanese KEI formula - and is not available in Canada or the USA. Closest thing would be Honda FIT, and it is still a few big steps above the Picanto

[clare]

More trouble than you need too.

[clare]

On a VW Golf??????????????

[clare]

The reason he didn't test 20s is there wasn't a 20 inch tire and rim combination for a VW golf, and they already determined things go down hill fast over 18.

[clare]

EVET larger rim tire I have ever worked with weighed more than the smaller rimmed equivalent. And I've worked with a lot of tire and rim combinations over the years. Surprising fact is MOST alloy rims weigh as much or more than the plain stamped steel wheel of the same size, too (Talking street legat rims here, not Magnesium race wheels or spun aluminum centerline drag wheels)