I figured I'd ask the more rev happy ppl in this forum to see if they have any insight on wheel weights and how they affect our cars.

I understand that the current Fit Sport rims weigh 15.8lbs roughly.. now I have been contemplating getting 17" wheels that weigh 18lbs. I know that isn't much of a difference, but the wheels I am also considering are a set of 15" 10.6lb wheels.

So the difference in weight between the 2 different wheels that I am considering is 7.4lbs.

Now this could be a pretty big number when it comes to how my Fit will perform seeing as we are just rated above 100hp...

Can someone fill me in with their knowledge? what are the advantages and disadvantages?

I'm not going to track my car, but I do like to drive aggressively and don't want to make my Fit any slower than it already is.

 

well look at it like this you lose 5.2 lbs on each wheel and youll end up losing lets say 1 lb on each tire (thats probably completely wrong but if you buy a set of low pros your gunna lose weight so now youve lost 25 lbs off your car every little bit adds up....so you do that then you get a carbon hood loose a few lbs with an aftermarket intake now you lost like 40 lbs on a car that only weighs 2400 lbs weight adds up quick now if you had a camero who effin cares lol i would say go for the 15s makes more sence to me :P but im a noob so doesnt matter what i think

 

nah through some 28's on it haha jk yes it makes a difference. my car loves the new wheels

 

Having not tracked my Fit yet, I can't speak to it effect of lowered un-sprung weight. In previous cars I've owned, lowered un-sprung weight didn’t seem to make a big difference. With a low powered car such as ours, lighter wheels and tires will improve driving characteristics to a certain extent for street driving.

The track is a different story. When you are trying to take a car to it's limit, lowering weight can make dramatic differences. Seeing as you don’t plan on tracking your car, I doubt you'll notice much, except for being slower if you pop on some big shoes.

I am sure someone here can better speak to the greater impact of lowered un-sprung weight versus just lowered weight. I remember reading the impact of lowered un-sprung weight was 2 or 3 to 1 versus overall weight loss (carbon hood).

 

Weight you save on wheels makes a lot more difference on the driving experience than the weight you save on the rest of the car; It's moment of inertia. The heavier a wheel is (18lbs vs 10lbs) , the more force is required to get it spinning. Also, the further out the mass is from the rotational center (17" vs 15") , the more force is required to get it moving. So you can see how lighter wheels will make a difference when you accelerate or turn. But the same also applies when you're trying to slow down. The lighter the wheel (rotating mass), the less force is required to bring it to a stop. Now times that effect on all 4 wheels, and we're talking a big difference here. And because it takes less force to spin the wheels, there's also some fuel economy that can be gained with lighter wheels (steelies vs alloys for example).

My previous B5 Audi A4 1.8t for example, I can run 15.5 quarter mile times at the track with OEM 15" alloys. But with my 18" Mille Miglia Spyders on, my 1/4 mile time increased significantly to high 17 seconds. Ask anyone who drag races. That is a huge amount of difference.

Hope this helps.

 

That does make a lot of sense.. thank you.

I would prefer to opt for better gas mileage, accel, braking and handling then going for the look of a 17" wheel.

 

Weight you save on wheels makes a lot more difference on the driving experience than the weight you save on the rest of the car; It's moment of inertia. The heavier a wheel is (18lbs vs 10lbs) , the more force is required to get it spinning. Also, the further out the mass is from the rotational center (17" vs 15") , the more force is required to get it moving.

Very well explained! And I can actually feel the effect of lighter wheels now that I drive with my summer shoes (lighter rims & tires). The difference is actually more noticable than with my AirBox or my CatBack exhaust mods... no kidding!

 

I think I am sold on the lighter 15" wheels over the 17s.. thanks a bunch guys. made my decision a lot easier!

 

my 16's are lighter than my stocks. but 15's are cool might buy some later down the road?

 

I have heard from some where that every 4 pounds of rotating mass you gane or loss is ruffly equivlent to 1 horse power gained or lost through the drive train. so what ever weight svaings or pound packing wheels you put on the car the 4/1 ratio only appleys to the drive wheels and the rest adds or sutracts to the cars weight. so if you free up about 12 pounds off your wheels you might gain about three hps. hope that helps.

 

Go with the 15's. You can't go wrong with them.

 

There was an article I read not to long ago that basically said that every pound of unsprung weight equates to apx. 10 lbs overall weight of the car -- i.e. if you cut 3 pounds of weight on your wheels, tires, rotors, etc. then it's like lightening the car 30 pounds, and the reverse is true as well. In my case, I was looking at some forged 16" SSR's that were like 11 pounds each and tires for them were 20, so one wheel tire combo was 31 pounds -- about 4 pounds lighter than stock 15's w/ tires. 4lbs x 4 wheels = 16 lbs unsprung weight, so about 160 lbs of overall weight savings. You'd have to tear quite a bit of crap off the car to save 160 lbs normally, so it's a pretty impressive gain.

 

Chikubi- If you can find the article or a link, it would be sweet! I could feel a dramatic difference in autox, but not much for the street with a previous car. If weight savings are that significant, they'll be about first on my list! This may be especially true for the Fit because of it's light weight (seeing as many other cars hover around 3000#).

G

 

It was " Why wheels are more than just tire holders", pgs. 111-114 in the 12/06 Modified. It's not the most detailed article by any means, but that factoid stuck in my head.

 

Chikubi- Thanks for pointing me in the right direction! I like to go back and read the articles even if if just for the factoid. It also helps for "nuh unh...ya hunh" arguments in forums.

G

 

Thanks for all the info everyone! I think I have made my decision to go with a lightweight 15" combo over the 17"s.... the 17's are wicked nice, but in the end I still think 15's can look great on our cars and I'll gain the performance/mileage outta the lighter wheels.

 

that is very interesting. I'm sure further studies can be done on this, but I like that thought. Maybe lightweight lugs aren't just bogus lol.. My 16's fortunately are lighter than the oem 15s so I'm happy.

 

Yes. The less rotating mass (weight) the easier it is for the engine to accelerate (and brake) so its worthwhile in drag racing or in road racing. The real secret though is lighter tires since they have a rotating radius much greater than the wheels.

 

I had 16x7 wheels on my Fit for a while, then switched back to the stock Fit Sport wheels, and noticed the difference right away. My mpg improved, and the car just felt lighter on its feet again. The 16" tire/wheel combo weighed nearly 5# more than the stockers. The wheels themselves are pretty equal in weight, but I think the extra weight came in the much wider tires. I really like the look of 16s, but the car just feels better with the smaller setup. People have said the same thing for years about Miatas and Mini Coopers. Some cars are just more sensitive to wheel weight, and maybe the Fit is one of those.

 

The weight of the wheel is not much of a problem when going at constant speed. If you drive the speed limit on the street or usually drive in heavy urban traffic then light wheels aren't going to be much help.

You gain an advantage anytime you have to speed up quickly, corner hard, or brake hard. As you accelerate you'll use less power to move the mass of the tires and wheels. Any weight savings in the tires, wheels, brakes, lugs or bolts will be helpful under those circumstances.

Lighter wheels while helpful are also subject to damage from road debris, curbs, and potholes so be very careful especially in combination with lower profile tires with stiffer sidewalls as is the case with 17" or larger wheels.

In your example the 15" wheel with lower weight makes the most sense. Also attractive would be a light weight 17x7" rim but cost would be fairly high to get that.

Another advantage of 15" wheels is you can use tires that fit which have 50 or 55 series sidewalls for a bit more street comfort vs 40 series like in 205/40-17.

Tires also vary in weights, some have a more robust construction as in All Season tires, Falken ST-912, while others are very light weight like Toyo T1R built for speed/handling. You don't have to go extreme on tire weight but do consider the whole picture, treadwear, handling in wet or dry, summer vs all season rubber and tread pattern. Some tires handle really well but do weigh a bit more.

If you are into any sort of performance driving then lower weight is a good goal. One or two lbs difference isn't going to be that noticable but 5 lbs loss per wheel tire combo is significant.

Low powered cars definitely are hindered more by heavy wheels (18x8), makes the car feel sluggish off the line. Imagine running on the track with heavy boots vs light racing shoes.

For street use, the Fit would do well even with some nice allow 14" rims.
For example Tirerack.com has Kosei K1TS in Silver and light grey finish
14x6 $104 each 9.3 lbs each +38mm offset fits-
175/65-14
185/60-14
195/55-14 Toyo Proxes T1R $71 each 16.8 lbs 280 treadwear Max Perf Tire
195/60-14
205/55-14 R compound tires

Stock tire and wheel 15x6 is about 34 lbs
4x6 K1 TS with Proxes T1R could be 26.1 lbs