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View Full Version : 17" rims and fuel economy


songa
12-17-2008, 01:18 PM
hey guys...anyone here running their yaris on 17" rims? although i love my FE on my stock (15" steelies), i am starting to consider putting 17" rims on there because of the looks. however, how drastic will this change affect the FE? lets assume that the 17" rims are about 20-21lbs each, which should be about 3 or 4lbs heavier than the stock 15" steels (which are around 17lbs each if im not mistaken). with that total of 12-16lbs heavier wheels, how much will that hurt the FE? and does it also depend on the diameter of the tires as well? i plan on using 205/40/17 tires. im not sure how much they should weigh tho. maybe this quetsion is a little too hard to answer =P if anyone has their own experience with 17" id like to hear them tho at least ! thanks

puetato89
12-17-2008, 01:36 PM
i love my 17"s.... and the mpg didnt change much... but the turning radius is a bit decreased... i dont know if me being lowered has anything to do with the mpg

songa
12-17-2008, 01:55 PM
ahh i love the yaris turning radius! how much do your 17"s weigh?

thebarber
12-17-2008, 03:41 PM
well, i have 14" steelies which weigh around 14lbs (i think 15" steelies are 15 or 16lbs) with 185-60-14 fuzion hri's

crandall has 17x7 tenzoR rims w/ 215-40-17 general exclaim uhp tires - - i think the rims weigh 18 or 19lbs....so not THAT heavy by 17" standards

we're both 5 speed, both live in the same town and he gets about 50km (+/- 30miles) less per tank than i do. he's dropped on tein basic coilovers and i KNOW he takes it easy accelerating....and he doesnt really speed. i drive moderately aggressively and i take off quick from lights. i also have an intake.

ive driven crandalls car too....i notice HUGE acceleration and braking difference between our two car (intake or not).

heavy 17's, in my opinion, arent a good idea for small, light cars with small engines and low hp - - if youre concerned about acceleration, braking or economy, that is...

jambo101
12-17-2008, 03:51 PM
I'd keep the original 15 inch with snow tires and get summer tires on the 17's for spring,or do you plan on getting snows for the 17's=very expensive.

songa
12-17-2008, 04:03 PM
what about all seasons on 17's?

thebarber
12-17-2008, 04:24 PM
what about all seasons on 17's?

not to run year round...

MadMax
12-17-2008, 04:30 PM
But remember, if you add 17" wheels then you need to multiple the distance driven by 1.07 to get the exact mileage, due to the larger wheel diameter...

So when I drive an "indicated" 350 miles, in reality it is 374.5 miles...

Cheers! M2

thebarber
12-17-2008, 05:12 PM
But remember, if you add 17" wheels then you need to multiple the distance driven by 1.07 to get the exact mileage, due to the larger wheel diameter...

So when I drive an "indicated" 350 miles, in reality it is 374.5 miles...

Cheers! M2

not really...its all about tire size

oem is 185-60-15

205-40-17 are within 1.23% of the oem rolling size

215-40-17 are within 0.125%

really, youre only going about 1% farther rather than 7%...

puetato89
12-17-2008, 07:50 PM
ahh i love the yaris turning radius! how much do your 17"s weigh?

all 4 was 44lbs... with tires it was i believe about 52-56lbs range... on 205/40/17

jambo101
12-18-2008, 02:30 AM
what about all seasons on 17's?

All seasons might be ok for southern climates but if you are in the snowbelt i'd recommend the dedicated snow tire.

MadMax
12-18-2008, 08:21 AM
not really...its all about tire size

oem is 185-60-15

205-40-17 are within 1.23% of the oem rolling size

215-40-17 are within 0.125%

really, youre only going about 1% farther rather than 7%...

My Yaris has 215/45ZR17 tires on it, and stock tires are 175/65R14s.

Go to this web site (http://www.1010tires.com/TireSizeCalculator.asp?action=submit&reset=yes) and submit those two sizes in, and you will see that the stock tire has a circumference of 72.09 inches (1831mm) whereas the larger tire I am running has a circumference of 77.31 inches (1963.6mm). That's a diameter difference of 6.75%.

Do the math and you will see the tire travels a distance of an additional 5.22 inches per rotation over the stock tire.

As the odometer is set for the stock tire, you must add the addition of 7% (rounded up) to the odometer distance traveled.

thebarber
12-18-2008, 09:08 AM
My Yaris has 215/45ZR17 tires on it, and stock tires are 175/65R14s.

Go to this web site (http://www.1010tires.com/TireSizeCalculator.asp?action=submit&reset=yes) and submit those two sizes in, and you will see that the stock tire has a circumference of 72.09 inches (1831mm) whereas the larger tire I am running has a circumference of 77.31 inches (1963.6mm). That's a diameter difference of 6.75%.

Do the math and you will see the tire travels a distance of an additional 5.22 inches per rotation over the stock tire.

As the odometer is set for the stock tire, you must add the addition of 7% (rounded up) to the odometer distance traveled.

it is suggested you dont go past 3% tire size difference....just because it screws up your speedometer and odometer too much otherwise...

MadMax
12-18-2008, 11:40 AM
it is suggested you dont go past 3% tire size difference....just because it screws up your speedometer and odometer too much otherwise...

I have never heard that one before, can you cite your source? Plus, if anything, that is probably a rule for stock rims, on which you can put slightly larger tires. But mine are aftermarket.

Plus, I own a Jeep, so I am very familiar with oversized wheels and tires! :headbang: It is very common in the Keep community for people to put huge tires on their rigs. Besides suspension modifications, the only real requirement for larger sizes is regearing (for going from 29" tires to 35" or larger); but that is not an issue here.

The stock Yaris with an AT can easily handle 17" wheels, and you can even lower it by changing out the springs to some degree without having rubbing issues. People all over this forum have done this, and there are numerous threads about it

Cheers! M2

thebarber
12-18-2008, 11:51 AM
I have never heard that one before, can you cite your source? Plus, if anything, that is probably a rule for stock rims, on which you can put slightly larger tires. But mine are aftermarket.

Plus, I own a Jeep, so I am very familiar with oversized wheels and tires! :headbang: It is very common in the Keep community for people to put huge tires on their rigs. Besides suspension modifications, the only real requirement for larger sizes is regearing (for going from 29" tires to 35" or larger); but that is not an issue here.

The stock Yaris with an AT can easily handle 17" wheels, and you can even lower it by changing out the springs to some degree without having rubbing issues. People all over this forum have done this, and there are numerous threads about it

Cheers! M2

jeep is a different story though...i have a buddy on 35's....he changed the gearing in his speedo though

as for a source of that 3% rule...1010tires.com, the place you linked to goes red if you put in a size thats 3% larger than your stock tires on the tire size calculator...see:

http://i22.photobucket.com/albums/b339/dabarber/1010tirescalculator.jpg

the tires you bought are sized for a corolla.....

MadMax
12-18-2008, 12:12 PM
I didn't get that message, and numerous people on here have put on 17" wheels without problems. Plus, I may be relatively new to the Yaris; but this isn't my first rodeo! The Yaris is light enough and the brakes adequate to handle the larger wheel. You may lose a little lower-end acceleration but you gain it back on the upper end.

As for Jeeps, I hope he regeared more than his speedo if he offroads, as his differentials are going to explode one of these days if he puts the stress of 35s on them with the stock gearing! He needs to regear to 4.88 with 35s to get the low-end back. Without that, he'll be very slow off the line and be downshifting at every hill even if he doesn't offroad.

TLyttle
12-18-2008, 12:20 PM
Welll.... One of the big flaws to current tires as I see it is the width. If wide tires were efficient, then bicycles would have wide tires, right? Every try pedalling a bike with fat, small-diameter wheels? It ain't easy... Same thing applies to any wheel: the larger the diameter, the less rolling resistance. The narrower the wheel, the less rolling resistance. All this rolling resistance has to do with fuel economy.

As far as snow is concerned, the same thing applies: my neighbour goes over a gravel pass in the winter, and none of the 4x4s, no matter what tires they have, can follow him. What's he driving? A Model T. 30" diameter, 3 1/2" wide tires. He can drive through a foot of snow with no chains or other traction devices. Gee, why is that?

I had a set of late-technology snowtires on my Volvo; they worked, but now I have a set of narrow-section (75%) tires on there, and they are much better in the snow (they don't plow as much), and my FE went up.

Something to consider...

thebarber
12-18-2008, 01:48 PM
I didn't get that message, and numerous people on here have put on 17" wheels without problems. Plus, I may be relatively new to the Yaris; but this isn't my first rodeo! The Yaris is light enough and the brakes adequate to handle the larger wheel. You may lose a little lower-end acceleration but you gain it back on the upper end.

As for Jeeps, I hope he regeared more than his speedo if he offroads, as his differentials are going to explode one of these days if he puts the stress of 35s on them with the stock gearing! He needs to regear to 4.88 with 35s to get the low-end back. Without that, he'll be very slow off the line and be downshifting at every hill even if he doesn't offroad.

no problems? but you said yourself that odometer is off 7%, that means your speedo is off too. as for acceleration, ive drive a yaris with 17's, and compared to my car w/ 14's, its a dog from a dig

as for my buddies jeep, its fairly extensively modded...he knows what he's doing....lol, i think! his screen name is highonlifeandglue on jeepkings.ca

MadMax
12-18-2008, 02:26 PM
What's up with all you Canucks?!? Do ya gotta argue about everything?!? :iono:

Just kidding, of course! For TLyttle, I do understand that a wider tire offers greater rolling resistance, therefore reduces fuel efficiency; but you neglect to mention that there are benefits over a wider tire such as cornering traction. By the way, you got it confused, the diameter of the tire is the distances encircling the tire, not the width. We are talking about taller tires on here, not wider ones; but the truth is that taller tires do require greater effort to get moving, hence the need to regear in Jeeps when adding much larger wheels.

For my buddy thebarber, the speedo and odometer being off by 7% is not a big deal. I can easily computer how fast I am going and I also have a GPS that gives me a more accurate reading than any speedometer would (I left the speedometer error discussion out of this as it applies pretty much equally to all cars). I work with a guy who has a stock Yaris with an AT, maybe one day I will challenge him to a drag race so we can see how much faster the smaller tires make it. I doubt it is much, and I would have him at some point as the taller tires will give my car a greater top speed. But all that is a moot discussion when talking about an economy car such as the Yaris. The larger wheels are more of a 'looks' thing than they are a 'performance' mod. And I am not one of those 'hypermilers' who play every trick in the book to squeeze an extra mile or two out of a gallon of gas. A gallon costs $1.45 here in Texas at the moment, and I would rather enjoy driving the car. I speed (80+ MPH), I take off from stops faster than a snail and I don't shut down at stop lights or drag off the back of large trucks.

I bought my Yaris because it is a fun little car to drive, and I put the bigger wheels and tinted windows on it to make it unique. I parked next to a stock Yaris the other day and there is a distinctive difference between it and mine.

And most of all, I am happy with it. That's all that matters. Oh, and if I want performance, I jump on my 150 HP litre-class sportbike. After riding that, nothing else feels fast...

BailOut
12-18-2008, 02:50 PM
MadMax,

Please remember that this is the Fuel Economy forum. The Cosmetic Modifications forum can be found from the main page.

MadMax
12-18-2008, 04:34 PM
BailOut

I didn't drive this discussion, I originally just added the fact that 17" wheels are larger than stock; so if anyone was comparing the two then they need to factor in the 7% increase in diameter....

But you are right, this isn't my area of interest and I wandered in here by mistake...so adios, amigos!

TLyttle
12-19-2008, 09:40 PM
Yup, we don't have much else to do up here in the winter..;-)

I have never been a fan of wide tires on small, low-powered vehicles; I am very aware of the cornering benefits of wide tires, and it would suit me if the only thing we required of our cars was cornering power. However, we need tire stability in the wet (hydroplaning is truly exciting alright, but not always desirable), and traction in the snow where wide tires are a disadvantage (hence my Model T analogy). We also fight for FE, and wide tires are again a disadvantage. The tire companies fight with these opposites every day, looking for the perfect combination of FE, traction, and long wear, under ALL weather conditions. Now there's a challenge...

I spent some time calibrating speedometers for a living, and I have intimate knowledge of how much difference an inch of diameter can make!

Herbicidal
12-19-2008, 10:32 PM
I'm running 205x40x17's so my speedo reading should be pretty close to stock. I have a GPS hockey puck antenna that I can hook up to my laptop and see how they compare. Maybe I can do that this weekend. Anyway, calculating my mpg using the trip meter of the car divided by the total gallons used for a fill up has ranged from a low of 29.7 (I had FUN with that tank! :biggrin:) to 35.2 at the high end. Usually I see an average of 32 mpg. I totally enjoy driving this car with the mods I've made. I'm really not concerned with my mpg as it is so much better than my 2001 Tundra 4x4 that gets about 14 mpg.

The Yaris is my daily driver (since June of this year) and the Tundra has gone into semi-retirement. So I'm ecstatic to get anything over 30 mpg. :thumbsup: By the way, the mpg did drop when switching to the 17's and a wider tire. If I recall correctly, the 17's with the tire mounted weighed about 6 lbs more per tire than the stock 15's that came with the 'S' version of the sedan.

As a side note, I'm running 35's on the Tundra. I regeared to 4.88's and I'm using a Superlift Tru-speed speedometer recalibrator. It is infinitely adjustable and I was able to set it using the GPS/laptop combo, so the speedo is spot on. I have not looked to see if there is a similar product available for the Yaris. :iono:

Herbicidal
12-20-2008, 05:22 PM
Today was a perfect day to transfer the GPS hockey puck out of the Tundra and over to the Yaris. Booted up the laptop, connected the GPS to the laptop via the USB port, launched DeLorme Street Maps 2008, acquired a signal and took off for a nearby highway.

The highway is nice and straight for about 6 miles. I tried different speeds and held that speed long enough to get a good reading from the laptop. Here's the results with my size tires (205x40x17):

Yaris speedo__________GPS
50 mph................................49 mph
55 mph................................53 mph
60 mph................................58 mph
65 mph................................63 mph
70 mph................................68 mph

So at highway speeds it was pretty much a 2 mph difference. At lower speeds the difference was more like 1 mph. Take the above info for what it's worth. :cool:

YarisPR
12-20-2008, 07:17 PM
I have 18" and I'am getting 30mpg on city. On the speedometer... I have no idea if its off but I have pass by cops at the speed limit according to my speedometer and no problem yet so I shouldn't that off.

MadMax
12-20-2008, 08:54 PM
(Yeah, I know I said I was bowing out of this thread; but I will keep this fuel efficiency related...)

Herbicidal

I did the same thing, I pulled the Nuvi 350 out of the Jeep and found that the speedo is alot closer than I thought. But that begs the question, how off is it with the stock sized tires?

For example, as with 17" tires we both have found that the speedo is actually near accurate; wouldn't that mean with smaller tires it would be more optimistic? For example, it would read 60 mph when possibly traveling at only 55 mph. As such, instead of traveling 60 miles in an hour, a person was traveling 55 miles, so their odomoter reading would be five miles higher than it should. For a tank of gas, that would equate to 30 miles that should be reduced if one is only using the odometer to compute their gas mileage!

I am going to have to go back and re-adjust my figures, it sucks that my Yaris isn't getting as good gas mileage as I thought (34-35 mpg); but with the wider tires and my driving habits, I am still doing alright. But the folks that are only using their odometers might find they aren't getting as good of gas mileage as they thought either!

And don't ScanGauge readers pull data from the same source as the instrument cluster (since the car is all electronic)? If so, those figures may be off as well.

Thoughts?

Oh, and the funny thing is that when I went with bigger tires on my Jeep; my speedo became more accurate as well!

Cheers! M2

Herbicidal
12-20-2008, 09:48 PM
MadMax, perhaps we need someone with stock wheels and a GPS to post some numbers and see what we get. Anyone? :confused:

YarisPR - you have 18's, but what is the tire size? If they are lower profile than a 40 series, then your speedo may not be that far off.

Kaotic Lazagna
12-20-2008, 11:44 PM
Being the same weight, if not lighter, than the OEM steelies, I actually saw a small increase in FE.