2007 Honda Fit Sport: The Secret of Tiny Wheels

as much as I like some of the big wheel design... When I got my aftermarket wheels for my sunfire, I was middle of the ground big, with 17's. there were a few people that put 18's on them, and if you went bigger that was rare air.
 
in 2001, the stock wheel size was 14, the middle 15, and the gt had 16.
 
The cobalt now starts with 15, and ends with 17.
 
the vibe starts with 16, and tops out with 18.
 
Thats nuts. not only are tires more expensive in this range. But you tend to get worse gas milage, and in some cases worse acceleration since now you have a huge amount of metal to start spinning around. Vibe would probably get 1-2 mpg better in the city with a 14" wheel vs the 16, and probably more vs the 18.

I don't think people realize the negative effects of large wheels and tires. Rotating mass is the worse type of mass for your vehicle...it's unsprung (so the suspension has to move it everytime your car moves), and your engine needs to move it everytime you go to accelerate. In the case of wheels/tires, your brakes have to slow it down every time you brake. And your suspension has to be able to adjust it when the bumps/turns come along.
 
But wheels and tires are more than that. They are the LARGEST gear (i.e. most distance from hub of rotation to outermost distance of mass on that gear) on the car. Therefore, they take the most effort to change direction (i.e. accelerate or slow down).
 
Great point about their packaging too.
 
Just to give a small example from my own life. I just replaced some tires on my 06 Civic SI. I had gone with some very lightweight tires (General Exclaim UHP). After 19,000 miles, I had a bubble in one tire and a nail in another so I decided to replace all 4. I kept one tire with the most tread and no flaws in it. I weighed it....16 pounds, verified also by showing as one pound heavier than a 15 pound dumbbell. So I had 4 tires weighing ~16 pounds a piece on my car.
 
I replaced them with tires weighing 23 pounds each. I gained 7 pounds at the outermost point of each of my rotating tire/wheel assembly.
 
My acceleration and braking has been tangibly affected. And I went with the same tire size!
 
Imagine if I downsized to a smaller wheel tire (like Mazda Miata club racers do)....I'd have longer brake life, better gas mileage, more acceleration, less stress on the suspension and a better ability for the suspension to adjust tire/wheel direction. Of course, I'd have ugly bigger sidewalls. Bleh.
 
:)
 
Joe

There is some corning benefit with a smaller side wall. But in 99% of cases that trade off is not worth everything else being worse.

It depends what you start with. If you have 14 inch rims with 75 series tires (like my old Buick), you see a big improvement by going to 16 inch rims with 55 series tires. Beyond that your wasting money and making your car worse. I have a friend who went to 18 inch rims with 40 series tires and they are terrible. They do handle a bit better but the ride is awful, they cost way too much and you really have to watch for potholes or you'll damage the rims.

Joe nailed the performance aspect of smaller wheels+tires vs larger ones, but the vast (99%) majority of the people who upsize their rims either don't know or don't care. It's obvious that Joe has some racing experience - I'm guessing SCCA autocross. It's unfortunate that he's in the minority.

Another reason for the bigger wheels is to clear the ever-increasing brake rotors and calipers. One example is that the stock IS250/350 18" wheels can't even fit on the IS F due to the massive Brembo brakes.

"I don't think people realize the negative effects of large wheels and tires. Rotating mass is the worse type of mass for your vehicle...it's unsprung (so the suspension has to move it everytime your car moves), and your engine needs to move it everytime you go to accelerate. In the case of wheels/tires, your brakes have to slow it down every time you brake. And your suspension has to be able to adjust it when the bumps/turns come along. "
 
You cannot assume larger wheels are always heavier. A car with 15" steel wheels and wheelcovers does not necessarily have lighter wheels than a car with 17" aluminum alloy rims. In addition, the design of the wheels has an impact on weight. Trucks tend to have large spoked, chunky rims that are very heavy. Sports cars typically have thin spoked alloy wheels that can be large and light.
 
On top of that larger wheels LOOK better and that is a major reason they are becoming more popular. Also, large tires are not always more expensive. The Goodyear LS tires on my car are like $100 from Tirerack. The standard tires on my old car (16s) were more expensive.

we need moderation when it comes to wheel sizes. Lets be honest: 15" wheels are no longer acceptable from a styling perspective. While there is such thing as going overboard (18s on compacts for example) we have to realize that today's suspension and tire designs are superior to what was available 20 or 30 years back and a car with 17s or even 18s can have acceptable ride quality. the Lucerne and DTS have 18s on 245/50 tires and maintain smooth ride quality.

1487 - Of course, you are correct. I stated the rule, not the exception.
 
That being said, switching to lighter wheels will sometimes still reduce the performance of the car. For instance, if you upsize to a lighter wheel but you increase the overall diameter of the wheel/tire combo, you'll push the mass of the gearing further away from the hub (as this is not a lineal increase in force, it is exponential).
 
Further, there is always a trade-off. Those lightweight aluminum wheels may be cast or forged. They may be more likely to bend or crack. I can get 14 pound 17x7 wheels for my SI for under $200 at tirerack, but will they last 2 years on PA roads? Probably not.
 
I also, in the last 9 months, bought two sets of tires in 215/45/17 sizing (stock size for my Civic SI). One set came out to $82 dollars a tire, the other set $72 a tire. You can definitely find cheap. Doesn't necessarily mean good (same thing for expensive tires though).
 
Felonious - I'm fast approaching a time in my life where I can afford to track my car(s). I've never autocross'd or driven on a track in my life. I'd like to get my SI on an autocross course. It's ready for one (albeit with 40k on the OEM Brake fluid and pads, it may need some freshening in that department).
 
Joe

^1487, I'm sure the cars are design to bear the new big wheels. To me its one of those things where funcation takes a back seet to style.
 
Even on my not design for sunfire. My orignal 17's came with some really high performance yokohma tires. Noise, rough ride.
 
when it came time to replace. I put on some decent, but cheap fuzion (bfgoodrich) tires. Ride got quiter and almost as soft as stock.
 
Still, knowing what I know now, i'd rather have gotten a 16.
 
Even if their nor heavier, alot of time the might use thinner spokes, but have a thicker rim, which puts more of the weight away from the hub.

Joefrompa certainly hit the nail on the head! I also can agree with Firstwagon, as I did a similar upgrade to my 1967 Firebird. From 205/70 14 inchers stock, I went to torq thrust D 15 inchers with 225/60 tires and realized a vast improvement in handling. I reallly didn't need to slap on anything bigger under the general rule of diminishing returns.

I hate that little 4-banger cars now have 17-18" rims and every soccer mom has 20's on her Explorer. I think it's a cliche that designers turn to when they can't come up with any other way to give their cars road presence. Look at some classic models, for instance. A classic Mini Cooper with 10" rims has more personality and presence than most subcompacts today wearing huge 18" chrome wheels.
 
It's like all they learn in design school is:
 
Fender Flares + Big Wheels = COOL!

"Further, there is always a trade-off. Those lightweight aluminum wheels may be cast or forged. They may be more likely to bend or crack. I can get 14 pound 17x7 wheels for my SI for under $200 at tirerack, but will they last 2 years on PA roads? Probably not. "
 
I havent noticed excessive wheel cracking in this era of 17" and 18" wheels. Most rims on production cars are cast which is likely due to cost. You can get more strenght and less mass form forged wheels but they are pretty rare as OEM rims.
 
generally speaking the higher the roofline of a vehicle the more it needs larger wheels to look proportional. I think cars like the Fit and Versa look ridiculous because of their high greenhouses and small wheels. SUVs and crossovers also look bad with small wheels. The less space between the fenders and the tires, the better. No one likes a car with wheels that look too small for the wheel wells.

Agree with the original post. The Fit Sport looks great on it's little 15"s. The wheel wells are also small, so they don't look too small. Nice design.
 
I don't like ridiculous over-sized rims, but when I see a Suburban or Tahoe on 15"s with 7" of sidewall it just doesn't look quite right, you know. We have 17"s on our Yukon and 16"s on the Mazda3. Both are the intermediate size - the base models had smaller wheels and the top of the line trim had larger wheels. I think they're both a nice compromise. Large enough to look like a nice upgrade, but not so large that ride and handling suffer. And replacement tires will be reasonably priced.

1487 -
 
My 17x7 stock wheels weigh 21 pounds. Most factory 17" wheels weigh around 20-25 pounds, 18" 23-28 pounds....all depending upon style, width, and formation.
 
Cast wheels are less likely to crack, but more likely to bend. They lose a little strength but aren't brittle. Forged wheels gain some strength but tend to be more prone to cracking (as opposed to bending). You can get a lighter forged wheel with higher strength, but if something happens to it you probably won't be able to repair it.
 
Cast wheels come stock (on most cars) for, like you said, cost reasons.
 
Also, most 17 or 18" wheels nowadays haven't truly gone to low-profile sidewall status. 225/45/17, a common tire size, has only 11mm less sidewall than a 205/55/16, which was a common size 5-10 years ago. Advances in tire construction also allow the 225/45 to absorb/dissipate road forces as well as those old 205/55/16 tires.
 
I love the original Mini with it's tiny wheels...but I don't think it has 4-wheel disc brakes :)
 
Whatever happened to the tweel? We're essentially there with our 22" wheels and 235/30 tires :)

FWIW, F1 cars use 13-inch wheels. :o)
 
See Article 12.4 of the F1 regulations:
http://jp.f1-live.com/f1/img/regulations/2008tech_en.pdf

Yeah Suby but F1 cars are just go karts with bigger engines. For a "real" race car check out the NASCAR cars.
 
Heh... : )

Low aspect ratio wheel-tire combos (short sidewall) also increases the likelihood you'll gash your wheel on the curb. Low profile tires often don't bulge out past the rim as much as taller tires do. And since many curbs angle away from the roadway a bit, taller tires give you even more room for error.
 
So for larger wheel/tires in general: more expensive wheels, more expensive tires, more frequent tire replacement (pothole induced bubbles or blowouts), more frequent wheel repair/replacement (potholes and curbs), slightly more frequent brake maintenance, etc, etc. Besides the "cool" factor (the better to show off those painted brake drums or OEM calipers), it seems like a win-win for the automotive parts/service industries.

My rims are lightweight 17" cast aluminum SuperAdvan V2. They may only weigh 14 lbs, but they sure are expensive.
http://www.mackinindustries.com/md/yokohama/superadvanracing.html
http://www.carspace.com/estreka/Albums/S2000/carlr.JPG
(sorry for link length)
 
Sidewall size does serve a purpose, even in the extremes (45 and below). While you don't need such low profiles on a normal car, they are imperative on many sports cars.
 
I bought some 255/45/17 tires for my rear wheels thinking a sidewall difference of 5 wouldn't make a difference. Boy was I wrong. When I took a turn at a normal speed, I first felt the normal body roll (very slight), but then I felt a sudden shift as the tires flexed. You think your entire rear end shifting an inch isn't a big deal, I'll tell ya different. That was heartstopping.

It's very unfortunate that this day in age with rising oil prices, automakers are producing so many vehicles with wheel sizes unpractical for their application (vs other alternatives). Although I'll admit though, the Fit does look a little odd with their small wheels at times for the same reason 1487 has stated, the higher roofline. Then again, it is a vehicle that caters to function over form.
 
joefrompa: I have an '06 Si as well and find that it's almost time to switch out my tires (~30K). I was thinking of going down to 16" in hopes of achieving better gas mileage as well as performance gains. Are their any wheel/tire combinations that you could recommend?

How's the transmission holding up?