Are these wheels worth it?
 

I have a chance to buy a set of used rims for my xB for $250 (with tires). They are the same size as the stock steel wheels, but are 13lbs each vs the stock 21lbs.

He says the tires are nearly new, and since I don't have stock or LRR tires on the box I'm not too worried about added resistance there.

However my current tires/rims are in perfectly good shape, and I've seen sets of stock rims w/stock tires in near-new condition going for $200 or less.

Will the 8lb/wheel give me any noticeable mpg improvement over stock? In particular am I likely to see enough to offset the cost?

Are you doing it only for the MPG benefits or also for a visual upgrade?

If I were you and I liked the looks of them AND they are lighter then I would go ahead and buy them. Sell the stock rims and tires you have and then end up with a fresh set of tires and lighter rims for not too much money.:thumbup:

In my opinion, if you are doing it just for the FE, then the answer is no on all accounts. if the wheels look cool and you like them, then yes.

not too many people on here talk too much about weight reduction. I have seen myself that there is a very minimal difference in FE when I ride alone vs when my friend rides with me (220lbs) there is a difference but you are only talking about 24lbs.

another friend of mine was talking about weight reduction and he said that you have to take 100lbs out of your car to gain 1 tenth of a second on a qtr mile. I am pretty sure that that is a rule of thumb as it depends on the weight of the car when you start weight reduction but you see my point.

I am sure that if you keep your car long enough or if gas prices go stupid then maybe you will recoup your money from that investment but it will be a long time regardless.

on the other hand, if the rims look cool and you like them and you get better FE, then go for it. I am sure it will take me quite a while to recoup the savings enough to pay for my scangauge but it is a cool piece of gadgetry and it was a good excuse for me to buy a toy.

thanks, that was what I thought.

They are neat rims, but I am always nervous about bending alloy rims, and super-light ones will probably be even more prone to that.

I'll have to think about it some more, but now at least I know I can remove "useful FE improvement" from the equation.

I can maybe help answer the question. I am going to be replacing my stock 13 steelies for a set of vx rims. Watch my gas log to see if it improves or not.

The way I envision it you may reap some rewards if you drive mostly city (stop and go), but you may lose some on the highway because the momentum from the heavier wheels also helps you along.

Those that know more may correct me if I am wrong.

You have to remember that each pound of rotating weight you save equals 3 pounds of stationary weight when it comes tostarting and stopping. So 8lb wheels over the stock 21 equals 13lbs on each wheel. Thats 52 lbs total, and a virtual savings of 156 lbs. Your brakes will apreciate that. Follow up with lightweight brake rotors and even pullies for your motor and I would think you would notice some kind of improvement...

I may have been unclear. The new rims are 13lbs each, *saving* 8lbs per wheel. For a total of 32lbs and a virtual total of 96lbs, or one skinny kid.

You are mostly correct, but the added momentum would really only help if you were coasting. The best thing to do is reduce friction before you worry about the weight. The savings while accellerating more than make up for the lack of momentum. At least thats what I found on a highschool team when we built a one person 'car' that got 6800mpg in a practice run and a solid 2000mpg from a 3.5 hp lawnmower engine.

I would like for someone to challenge this piece of folklore. I question whether it's true or not. In bicycling, where such issues are FAR more important because its not only our own speed but indeed our own legs, muscles, and pain on the line, the most scientific and logical arguments I've seen were that it is in fact a myth.

I spent quite a bit of time in rec.bicycles.tech for awhile, where there are some real experts who have the credibility and research to back up their claims and arguments, and I do recall that such people did not buy into the "rotating weight is worth more than other weight" stuff. I also learned about tire pressure, tire width, and rolling resistance; and some of what I learned is counterintuitive but definitely true.