Handling (15" vs 16" wheels)

It is possible but the benefit is still going to be realized with the quick ratio if your enjoy quick responce.

We don't know the offset of the wheels but obviously they did not want to increase the track for goodreason,presumably for efficiency and in maintaining good MPG compared to the 15" but still having the added benefit of improved handling.

I am sure the engineers did the best with the criteria and application they were working with and it has certainly paid off to say the least.

Oh come on! 15x5" 175/65/15 Front 35psi rear 33psi vs 16x6 195/50/16 Front 32psi rear 29psi. So the 16s don't have more contact patch huh?

Im glad the both of us got what we wanted. Believe me, I can't thank Toyota enough for making the C and an optional larger 16" wheel with the quick ratio. If you do change your wheels in the future, please keep us posted on issues if you go larger than what steering allows. I would like to see those calculations J Also others with the 16s have commented on the radius being better then they though. I have been able to make u turns on 1 lane roads with no problems at all. The radius is only 6 feet more! hehe

Come on we are talking ratios on the C so lets stick with that eh?

Yes, you will also need to address the steering lock issue which I assume is not related to the rack but adjustable possibly on another point? Otherwise, its going to be a difficult and costly to do a rack swap.

 

Yes but there association has an important effect on the overall driving experience for those seeking maximum Prius C eco handling fun from the showroom . I have never been offerd a chose in steering ratios on any car purchase so that is a first to me. Having the 15" doesn't mean you still can't have fun driving the car around corners but there will be a compromise. Im woundering how much higher I can get that .83g with all the Cusco parts out now?

 

It's tough to measure tread width but the 15" sports a 5.6" tread width and the 16" wheel sports a 7.1" tread width. Approx. # using the same model tire.

 

ron

 

The steering ratio really has nothing to do with the turning circle. To avoid rubbing they limited/shortened the total available travel of the steering rack, which means it takes less turns to go from lock to lock because the wheels don't turn out side to side as far. The steering ratio is independent of turning circle...


ron

 

yes, there is some benefit, but at the expense of the turning circle. it depends on what the buyer prefers. my opinion is that the slightly quicker steering does not make up for the large increase in turning circle.

if they kept the same offset as the 15's there would be no change in track and the wheels would stick out "only" 1/2 an inch. i'd love to know the official reason why toyota didnt just do this... instead they change the offset and change the steering rack to compensate? why? its like this on the prius liftback as well. the 17" wheel option uses a different steering rack.

others have also commented on how they hit full lock much earlier than anticipated when they park. 3 feet is a big deal when you are trying to park in a tight spot. like i said, it depends on what the buyer prefers. those of use who live in the city may prefer the tighter turns vs the quicker steering.

its a perfect example of how steering ratio by itself means very little.

it's 100% because of the rack.

 

actually, imo they quickened the ratio to compensate for the reduced travel.

 

You have to be careful with this unless you're measuring the actual tires because there can be big differences in tread width between makes/models of tires.


ron

 

You know I know that, Ron.

That is why I compared the exact same tire. Even then we cannot rely on these numbers 100% but comparing other models in these two sizes the difference stayed pretty much the same.

http://www.tirerack.com/tires/tires...5EL40002&vehicleSearch=false&fromCompare1=yes

 

How would a quicker steering ratio compensate for the reduced travel?


ron

 

Ludicrous fast? LOL

 

I was just sayin' . I did see you qualified it by saying approximate.


ron

 

Because I know folks like you will come in and correct me if I don't treat each post like a game of horseshoes or hand grenades. Close is good enough. LOL

 

the large turning circle is caused by the reduced travel of the wheels (i calculate 75.5 degrees total for 15" wheels and 62.2 degrees for 16" wheels). and so, they wouldnt use the same same steering rack, they'd use a different one with a quicker ratio. this is the same as the prius liftback with the 17" wheels. it needs a different, quicker steering rack.

 

Had to copy quotes into the reply since it didn't not include them? Hmm

One is quicker period! 8.3% is very noticeable when you snap the wheel. If you had 8.3% less MPG it would be significant and noticeable. If you had 8.3% less engine power it will also be significant and noticeable. I am a hyperactive C driver so to me ill take all I can get. You must be more calm and so it may not matter to you that much.

Opps made an error while I was doing to much stuff at once but changed it. You reply fast hehe.

Umm no point here. Unnecessary rebuttal

 

Wow the liftback has an optional 17" wheel? Wounder how those do on MPG?

 

2mpg less or more. I say 3-4mpg and some unarmed PC member says 1.5-2mpg.

The GenII loses about 4-8mpg with 17s depending on tires and other factors. The GenIII with aftermarket 17s loses about 3-6mpg it seems. We have two members testing this out right now. That being said, some can still pull off a 50mpg tank with the 17s but it is not easy unless you have a good commute or your hypermile a little. It takes summer temps and some serious effort for me to get a 50mpg tank in my old GenII on 17s. On 15s the same effort would result in a 57-59mpg tank.

 

The speed of the steering has no effect on the turning circle. Are you possibly thinking that the "faster" steering would make it less time consuming to crank the wheel back and forth when jockeying to park or something? If that's what you were getting at, the very slight difference in the speed between the two wouldn't even be noticeable. Like I mentioned in one of the earlier posts, the difference between the two ratios is only two degrees of wheel turn for one whole turn of the steering wheel. If they sped up the steering enough to make parking easier you'd never be able to drive the car on the freeway. It would be "Ultra Twitchy" . There are "variable" power steering units that do that kind of thing just to make slow speed maneuvers easier though.

But the steering is not "8.3% quicker". Like I said before, the difference between the two is just a bit over two degrees of wheel turn from a whole complete turn of the steering wheel. One full turn of the steering wheel moves the tires 25 degrees with the standard rack, and 27.27 degrees with the "quicker" rack on the models that come with the 16's.


ron

 

Interesting, it may not seem like much but I guess when a wheel on the road is turning at many rotations, the impact of a those extra degrees can be felt. If the wheel was off aliment by 2.27 degrees it would pull very hard to one side. Also having a larger diameter rim would also have the effect of a lower ratio as well no?