Handling (15" vs 16" wheels)

Just buy a Pc2 and then install after market rims with tires of your choice. Keep in mind a stickier and/or wider tire will affect gas mileage.

The 16" rims that they have on the 4 has a quicker steering ratio, but also limits lock to lock which results in a wider turning radius.

 

Does the c come with a rear sway bar, and other handling items? The regular Prius does not, and adding that has really enhanced performance. Really. I am sure the c will have more aftermarket upgrade options than the regular Prius.

 

c does not come w/ a rear sway bar, but they are available.

Suspension Upgrades for 2012 Prius C, Strut Tower Bar, Chassis Stiffener; Juicedhybrid.com

 

just buy the PC2 and save couple thousands dollar. wait for all the performance part and put them in.

 

And the steering ratio isn't really significantly faster anyway. It is a bit quicker but not much...

ron

 

From one Mazda owner to another, get the 16" wheels you will be thanking me! If you want to have that fun feel and take some hard corners you will be glad you got them. The steering ratio is also very important and will bring it closer to a Mazda feeling car as well. I got 58.3mpg and went 510miles on the tank with the 16" so MPG is still good with them.

 

nope.

 

lets present some numbers for the 15" wheels vs the optional 16" wheels

Turning circle:
15" = 31.4
16" = 37.4

steering ratio:
15" = 14.4
16" = 13.2

turns lock-to-lock:
15" = 3.02
16" = 2.28

front/rear track:
15" = 58.3/58.1
16" = 57.5/57.3

suspension: EXACTLY THE SAME despite what some reviews say...

so what does this all mean? steering ratio actually isnt all that different. also look at the track numbers. the 16" wheels actually have a narrower track, which means the offset of the wheels must be more positive, and so the width gained per wheel is actually more on the inside! that width gained on the inside necessitated the lower turns lock-to-lock, which causes the larger turning circle.

so if you have the 15" steelies, whats a man to do? buy aftermarket wheels. keep a similar offset and you will have no scrub radius issues. the width gained will be equal on both the inside and the outside therefore you keep the tight turning circle. kkim has already test fit 195 tires on 6.5" wheel with no rubbing issues on stock suspension.

the moral of the story? dont become enchanted with the 16" wheels and the minutely quicker steering ratio that it needs. instead, you can go aftermarket for wider wheels and keep the tighter turning circle that came with the "slower" steering ratio of the 15" wheels.

EDIT: just for fun, lets look at the 2012 mazda miata's numbers:

Turning circle: 30.8
steering ratio: 15
turns lock-to-lock: 2.7
front/rear track: 58.7/58.9

 

If yu don't mind a mild mpg hit then get the 16s or save the cash and buy a set of 17s. Fun factor goes way u with the larger wheels.

If you are lucky and drive well like priusCpilot then you can still pull off awesome tanks like he/she did.

 

This is exactly the reason I did not go for a 4 w/ 16s. Good clarification. :thumb:

 

On a car like Prius C small changes will impact the end result. The ratio will be noticeable to drivers and engineers felt that it was important enough to have a different rack put into the car to further benefit the driving experience. Lock to lock there is a difference of about 25% less with the 16†wheel. Keep in mind that tire type and size will play a big roll on the car. When you go to a 16†over 15†the contact patch will be greater and with the tire size over the 15†wheel you also have lower profile tire so less side well flex and greater stiffness and response. You also get more contact area since it is a wider tire over the 15†wheel. Also, there is the tire type and spec of the tire which on the 16†will also be stickier with a tread ware of 260 vs 300 on the 15†tire size.
Toyota engineers took the time to give optimal combination of good handling and MPG with the specs on these wheels and tires. I personal would not have the rims offset changed if I changed wheel to stick outside of the fenders. It will not look right and will affect drag even more than it needs to. They are only producing 10% of the Cs in Trim 4 and only 4% will have the 16†wheel option according the dealer. Im sure with such low numbers they will be hard to find in the used car market when people are will want to have the rarer optional quick ratio steering and factory wheels. The 16†are most definitely not for everyone especially if your only concern in MAX MPG. It has not been hard for me at all to get over the 50MPG mark with them. It has been estimated the 15†should give about 2MPG more over the 16†. Since you are concerned and posted about it I would say get them unless you no longer want to get the closest possible driving experience that the Mazda 3 gave you in the C. I was looking at the M3 and MT tested one at .95g avg with a steering ratio of 12.5 and the C got .83g avg on the factory 16†wheels and tires with a ratio of 13.2. For some that don’t want to pay for the Trim 4 and get the extras to get the wheels then I think getting the exact spec of the 16†wheels offset and all will yield the best results overall.

 

The difference in the number of turns lock to lock has very little to do with the steering ratio though. On the C that difference is almost all due to the shorter/limited overall travel of the rack they built in to keep the tires from rubbing the inner fender wells. The steering ratio itself is only 8.3% quicker on the c with 16's. As far as skid pad numbers you noted go, the difference between .95g and .83g is actually pretty significant with the c coming up a fair amount lower. What would be the more interesting comparison would be to see the numbers between the c with the 15's and 16's...


ron

 

...and what would that offset be? no one has provided the answer to that very question which I asked weeks ago. I believe the stock 16" alloys are 6" (?) wide... but what's the offset?

my guess is that it will be in the 50-55mm range. If that's correct, there are very few aftermarket rims with those types of offsets. Besides, if you don't have the steering rack that limits travel, you can't use those specs w/o the rims/tires rubbing the inner fender. That's a guess as to why Toyota used a limited travel rack w/ those 16" wheels.

 

you have it all wrong. the engineers didnt add the quicker ratio for better handling. the 16" wheels have a more positive offset. therefore in order to prevent rubbing on the inside of the wheel, they had to cut down the turns lock-to-lock. cutting down on the turns lock-to-lock increases the turning circle diameter. in order to slightly compensate and decrease the turning circle, they had to lower the steering ratio.

now at this point you may say, "why then do fast cars like the M3 have a super quick steering ratio? a large turning circle? low turns lock-to-lock?" the answer is very simple. bigass tires. however they have additional tire width on both the inside and outside of the wheel. the 16" wheels gain width mainly on the inside, hence the narrower track numbers vs the 15" wheels.

so the REAL question is, why is the offset on the 16" optional wheels so crappy?

mentioning contact patch size WITHOUT mentioning tire pressure? and then there is also the theory that, for a given pressure, wider tires do not change the contact patch size, but only the shape. whatever. that is another discussion for another day.

this is the crux of the discussion. this is IMO what made reviewers think the 16" wheel option also includes upgraded suspension. this is also what complicates the steering ratio discussion. a truly scientific approach would be to test both 15" and 16" on the same steering ratio and THEN see if there is a felt difference.

lol sounds like you are rationalizing your purchase. i did all the calculations, analyzed all the numbers, before buying my III. the simple answer to the crappy 15" steelies will be answered in the aftermarket... and i get to keep the tighter turning circle. it's win-win and this is what i would recommend to others. if you are averse to buying aftermarket wheels then by all means get the 16" wheels. but test drive it first and make sure you can live with the huge turning circle. to some its a big deal. others, not so much. YMMV. imo replacing the 15's with better aftermarket wheels is the best of both worlds...

the miata has a 15:1 steering ratio. are you proposing the 16" wheeled prius c is better steering than a miata? looking at just numbers is silly eh?

uhh... NO... there is a reason why they shortened the turns lock-to-lock with the 16" wheels. and its not for more sporty steering per se...

 

being that the track of the 16" wheels is 0.8" less, that's 0.4" on each side.

0.4" = ~10mm.

so assuming the track difference is all due to offset, add 10mm to the offset of the 15" wheels and you get 50mm. so my estimate is spot on with yours.

 

I know the difference has little to do with each other but just pointing out the difference in percentage is all.

To expect a C to be an M3 is not the point but the fact that for a Prius its not bad and just the ratio being quicker by 8.3% on the 16s the same way the grip is less then 12.5% vs the m3 so why would 8.3% not be significant yet 12.5% is to you? The numbers are real good for a little eco car if you ask me. When it comes to steering ratios a little makes a lot of difference and quite frankly they got it just right for the car if you ask me.

 

I wasn't able to find the offset but yea the 16"x6" and 15"x"5 for the wheels. Im also not sure if the steering rack controls the radius or if its in the stoppers which may be adjustable.

 

Because skid pad g force numbers and steering ratios are two entirely different things . I would think that the steering ratios on both of the C versions are plenty quick enough for sporty type driving.


ron

 

Perhaps with 18"?