I'm thinking about getting some smoothies. They are 21lbs each. I believe our stocks are about 9 lbs each. Will this have significance in drivability, mileage, etc?

It will, but probably not that noticeably. The rubber you use will make the most difference in how it feels.

This is one of those items that is debated a lot and people have varying opinions on the effect.

Do a google search for "unsprung weight". This is why heavy wheels have a detrimental effect, IMO.

I think the stock wheel with tire runs 37 lbs. My maglites are 14lbs, not sure about the tire, tho...

I'm thinking about getting some smoothies. They are 21lbs each. I believe our stocks are about 9 lbs each. Will this have significance in drivability, mileage, etc?

Stocks are more like 19lbs each. I don't think you'll notice a difference.

there won't be a huge difference in going from 19 to 21 lbs...but I would recommend getting the lightest wheels you can if handling, response, and fuel economy mean anything to you.

Every ounce counts when dealing with unsprung weight especially.

it's a two pound difference on each wheel. four wheels means you're adding eight pounds of unsprung weight.

i don't kno how true this is, but i've heard that each pound of unsprung weight is equivalent to four pounds of sprung weight. so, by adding eight pounds of unsprung weight, you're essentially adding on 32 pounds to the car.

it's a huge difference.

32lbs.... you're not going to FEEL the difference.

1 gallon of 2% milk = 10.2lbs.
32lbs = 3 gallons of milk.

If you go buy 3 gallons of milk after work... when you get home, what's your thought for the rest of the evening? "MAN! THOSE 3 GALLONS OF MILK IN THE BACK OF THE BOX JUST KILLED MY GET-UP-N-GO ALL THE WAY HOME!"

......no

Ha ha ha ha. Beautiful analogy windowtint, just beautiful.

The rule of thumb for unsprung weight is that one pound is the same as 10 pounds of sprung weight. So 32 pounds would be like adding 320 pounds to the car.

Ever notice the car drive a little worse when you have two people in it with you compared to when its just you? It would be about that same difference. Some people wouldn't even notice, some people would be really bothered by it...

That is B.S. - your saying that adding wheels that weigh just a tad more is like adding 300+ pounds!

YEAH right!

Hows this, Ill get two of my buddies to drive around with me, then take off the stock wheels and put on my 18" TRD's, drive it by myself, and it should "feel" the same?

Not....

Yes, that's exactly what I'm saying. Take it to a track and get quarter mile times each way. Or just ask some of the regulars at the track about unsprung weight.

Its the same reason performance pulleys are made as lightweight at possible - every pound of moving parts saved is like taking 10 pounds of non-moving weight off. Its also why race cars use wheels made from extruded (not cast) aluminum - its the lightest possible material in one of the most critical weight areas of the car.

Quoted from http://www.mickeythompsontires.com/tech_tube_tires.html

"4. Weight & performance
In some cases it is acceptable to run a racing tire without a tube. When a car competes in a heads up class, unsprung weight is an important factor. Tires and tubes are all unsprung weight. One pound of "unsprung" weight is equal to 8 pounds of "sprung" weight. The average tube weighs about 6 pounds. Therefore, if you eliminate the tubes you have eliminated the equivalent of 96 pounds from the car. For every 10 pounds of unsprung weight removed you may pick up as much as .01 seconds in quarter mile ET. "

Just as an FYI: TheScionicMan stated that he thought the factory wheels, I'm assuming he's referring to the steel wheels with hubcaps, including the tires are 37 lbs. each. I have the Enkei 17" rims bought from the dealer. I brought one in one day when I was putting new springs on and put it on the scale. It came to 38 lbs.

Eight? Used to be 10... :)

Oh well, at least an expert is backing me up... THX.

my physics professor went over this with me. rotational inertia is a little different than inertia of a block to be pushed or sumthing. the farther out the weight is from the point where torque comes from, the more torque is needed to move that mass.

32lbs may not be the correct equivalent weight added, but the point is that heavier wheels means sarificing performence. you don't have to believe us, but we're just trying to help. i say that you should buy those wheels and prove us all wrong if you feel strongly enough about the trivialness of wheel weight.

Well I will agree that unsprung weight will make a difference- but to "feel" 300 lbs worth?-

The added weight of rotating mass will make a significant difference. The analogy that it would be like adding 250-300 lbs. in the back of your car is correct. Will also make a signicant change in handling. Sometimes however, this is offset somewhat by the improvement of grip, from, say a 17 inch, lower (and wider) profile wheel vs. the skinny little (and taller) 15 inch wheel. Having said that. The best overall wheel and compromise between looking good, handling good, and acceleration would be found in a nice LIGHTWEIGHT 17 inch wheel. All those using 18s and 19s will say they can't tell a difference between performance are just trying to justify looking good over performing well. That's fine. Heck, this is a Scion. If we were really interrested in performance, this is not the best vehicle to start out with. There is nothing wrong with just looking cool. 8)

If you are looking to truely improve your performance though, do not go any bigger than 17 inch. And keep it light. No chrome!

Lightweight wheels have another drawback - if you hit a pothole or curb them, they are far more likely to have irreparable damage. Its why lightweight wheels don't come stock on all cars in the first place.

To go really lightweight get extruded aluminum, not cast. An old friend of mine had them (wrapped in Hoosier's) on his grand national, and just that change alone took 4 tenths of a second off his quarter-mile times. That thing was BUILT - ran in the 12's!

The rule of thumb for unsprung weight is that one pound is the same as 10 pounds of sprung weight. So 32 pounds would be like adding 320 pounds to the car.

Ever notice the car drive a little worse when you have two people in it with you compared to when its just you? It would be about that same difference. Some people wouldn't even notice, some people would be really bothered by it...

You just completely went off base and misinterpreted what I was saying entirely. It helps when you read and comprehend an entire thread first.

The 32lb figure comes from the post that I was replying to... where it says it's a two pound difference on each wheel. four wheels means you're adding eight pounds of unsprung weight.

i don't kno how true this is, but i've heard that each pound of unsprung weight is equivalent to four pounds of sprung weight. so, by adding eight pounds of unsprung weight, you're essentially adding on 32 pounds to the car.

see there... A TWO POUND DIFFERENCE PER WHEEL! Hence, and OVERALL EQUIVALANT TOTAL OF 32 POUNDS OR ROTATIONAL UNSPRUNG MASS. Not this made up 320lb figure.

Sorry, all those gallons of milk made my head spin :)

If he's only adding a pound per wheel, then you're right. For some reason I had it in my head he was adding something like 12 pounds per wheel.

Oh, I know why... the ORIGINAL POST OF THIS THREAD says he's adding 12!!

Sheesh. Just because a response follows yours doesn't mean its automatically directed at you.

About curbing lightweight wheels: forged lightweight wheels are stronger than cast wheels of the same weight, so its more of a construction thing. Another benefit of not going larger than 17 in is that you have more tire protecting the rim, unlike those 18 and 19 inch wheels with those thin little rubber bands!

Man, This was a VERY educational thread. Thanks for the info! (So there are physicists on Scion life too!)


Rog

Wow, if our stocks are 9lbs each then that makes them lighter than most aftermarket Racing wheels. where did you get that number?

I don't think 9lbs is correct - the only way I can figure he got that number was the tire fitment thread says they weigh 37 lbs "a set" which I think is referring to a tire AND wheel as a set, not a set of tires ands wheels. They definitely weigh more than 9 lbs - I carried them to the shed...

i have 19s which wiegh 18 pounds and i think the size of the wheel makes more of a difference with acceleration than with weight from personal experiance. ive had 18s that weighed more but felt a little less sluggish :roll: smaller wheels have a smaller diameter and it takes less power to spin them . . or maybe im wrong

Diameter is a totally different thing and should probably have a topic of its own.

For diameter, the important measurement is the TIRE, not the rim itself. Its one reason low-profile tires are used with large rims, to keep the diameter down.

A small overall diameter will make the car accelerate quicker *IF* it still has enough grip to get good traction. It will also cause the car to have a lower top speed, and it will make overall traction WORSE so you don't want to overdo it on getting smaller tires.

On the other hand, if you are making serious power, you will need a taller tire anyway just to get decent traction. But that hurts acceleration, and increases top speed.

Its why a good reading of 60 foot times is important in dialing-in the car for quarter-mile drags...