25mpg?

[HerrStig]

I've seen a number of articles on "Plus 1" tire upgrades and the
general conclusion is to keep to the door jam tire pressures. What do the racing boys do to set pressures - measure tire temps across the tread with a "tire pyrometer" and adjust until the temps across the tread are the same. That gives them a baseline. "Blowin' em up to 51" 'cause it says so on the sidewall provides max load capacity for a car full of hefty folks and their luggage at the expense of wear (the center goes first) ride, and grip - the profile of the tread as it contacts the road is directly related to the amount of weight supported by the tire.

 

[Rolla07]

Originally Posted By: JHZR2
Originally Posted By: Silverado12
Did you get your speedometer recalibrated? That would make a big difference.


+1.

I dont get why someone would put 17" wheels on an econobox.



Ughhh because it looks better???

 

[supton]

IIRC our Camry came with 16" wheels. One of the last vehicles to buck the trend to "taller is better". At least that is my recollection, maybe it's got 17's... I'm certainly not looking forward to replacing the 18's on my truck! But that's the rage these days. I can appreciate the desire to go to better looking rims, at least if they are lighter than steelies.

Sounds like more drag, maybe not enough tire pressure, and possibly a heavy wheel. Might need a tank or two to truly establish real mpg.

 

[HerrStig]

Originally Posted By: Rolla07
Originally Posted By: Clevy
You have added weight,and rolling resistance if wider however I suspect the diameter of the outside of the tire hasn't changed much.
So you put 17" rims on a corolla.
How about drag radials up front for track days,maybe some under car lighting,neon perhaps.
And some blue light strips for the floor. Ballin"


Sure, make the assumption that because I put 17 inch rims on a corolla that I am trying to mod it. Sorry you never heard of putting mags on a car to make it look better. Everything else is stock and its purely because it looks better than [censored] stock 15 inch rims/tires. Dont judge people.
Toyota went from OEM 14's to 16's on the Camry in a matter of 5 years or so.

 

[Rolla07]

Thanks for the great replies guys! Im going to up the psi abit and play around with some different things.

 

[Smokescreen]

Yep, too wide and heavy.

You put on rubber that is even wider than what came with a 2012 Corolla Xrs with 158hp/162Tq.

Upsizing your wheels doesn't automatically make your car handle better. In a lot of cases it causes it to have slower acceleration and lower fuel economy. http://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested

I keep mine at stock sizes but put on lighter wheels and my fuel economy went up.

 

[gathermewool]

Originally Posted By: Silverado12
Did you get your speedometer recalibrated? That would make a big difference. Have you checked your speed on a GPS?



Originally Posted By: JHZR2
Originally Posted By: Silverado12
Did you get your speedometer recalibrated? That would make a big difference.


+1.

I dont get why someone would put 17" wheels on an econobox.



There are calculators online, one of which I used in the post just above yours.

Originally Posted By: gathermewool
Originally Posted By: oilstudent24
Do the tires turn less revolutions per mile causing less miles to appear on the odometer to calculate MPG? I dont know if you have an option to change the odometer to varying sizes of tires to get a proper reading Speedometer and otherwise


Quick calc reveals the following revs/mile:

Stock: 807.8
New: 808

1. Width: The new tire is over an inch wider (30mm,) so contact patch and drag will increase.

2. Rolling Resistance: What types of tires were the old vs new? Economy, with min rolling resistance replaced with summer tires?

3. Weight: How much do the new "mags" weigh compared to the old?

Also, adding more info in your thread title helps. No offense, but I usually make it a point to ignore vague threads. I'm honestly not really sure why I clicked on yours, since it's not much better than a "help, I gotsa a problem" type of thread.


Can we stop the holier than thou posting? He didn't post pics and ask for our opinions on that wheels.

 

[Quest]

@OP:

Your problem mainly lies on the rolling resistance of your new tires.

Different types of tire compound will result in different rolling resistance (aka "grip"). Some high-perf tires typically sacrifice rolling resistance for more "grip", some avg joe daily tires (all seasons, LRR type of "green" touring/all-season tires, etc.) will result in better fuel economy due to lower rolling resistance.

wifey's camry suffered from avg of 4mpg fuel economy loss when the original GYr Affinity tires were replaced with Uniroyal Touring (no size change). And recently when we replace those worn Uniroyal with [censored] Tourenza serenity, mileage (avg) upped by 3mpg...

Go figure.

Q.

 

[IndyIan]

Do you know what the alignment is on the car? I imagine any significant toe in or toe out, now creates alot more friction with wider low profile tires. I found on my Neon that running high profile tires on the street allowed me have all sorts of camber and toe for autocross, with only moderate wear due to the alignment.

 

[Vikas]

I would have never guessed that tires could cause 10 to 20% change in mileage.

 

[toeout]

I had 1998 Suzuki Esteem with 175/70/13 tires. I bought new 15 wheels with 205/50/15 tires and my mpg went from 34-35 to 29-30.

 

[71Chevyguy]

No need to recalibrate since you are using the same size tire for a 17" rim. If you did not get an alignment after putting the larger wheels on you may want to do that because if it is off and it probably is then you will shred your new tires. As for tire pressure, you may want to do some investigating as to what pressures are recommended on corolas that did come from the factory with 17" wheels. That would be a good starting point. Don't remember which place but i think one of the online tire places had that kind of factory info available for each size. Costco is another place that would have that info available but not sure if you have any in your area. Your loss of MPG is probably from the heavier wheels and wider tires though.

 

[javacontour]

I would be interesting to learn what the weights are of each wheel/tire combo? What did an original wheel/tire assembly weigh and what does the new 17" wheel with tire weigh?

Most folks don't end up with lighter assemblies unless they spend some serious bucks.

In this article: http://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested

they experienced a 10% drop in fuel economy and slower acceleration from 0-60 when going from 15" to 19" wheels

I could see something similar if not worse when you add in the variable of a different tire. (they used the same tire and wheel in all but the stock configuration)

 

[javacontour]

Just wanted to add, when I went from 16" wheels to 17" on my 98 SVT Contour years ago, I did manage to go to a lighter wheel. O.Z. Superlegera wheels. So I dropped 4-5# per corner with that setup over the stock wheels.

Better handling and a faster car due to less rotational and unsprung mass, and 10mm wider tires. Went from 205/55-16 to 215/45-17, IIRC.

 

[The Critic]

Originally Posted By: sciphi
I'd up the air pressure. 30 PSI is fine for skinny, tall OEM tires, not low-profile 17's.

Also, how heavy are the new wheels? Some aftermarket wheels are very heavy, while others are light.


Although some are probably going to roll their eyes at me for saying this, but it has been well-established on the prius forums that you will lose approx 10% in fuel economy when moving from the 195/65-15 tires to the 215/45-17 tires on the Gen III Prius. The agreed explanation for this phenomenon is that the wider contact patch increases rolling resistance.

Also, the Prius 5, which comes with the 215/45-17 tires, specs 33F/32R for tire pressure, whereas the Prius Two, Three and Four all specify 35F/33R. At least for the Prius, the larger tires must have extra load carrying capacity which allows lower tire pressures to be used.

 

[Rolla07]

Originally Posted By: The Critic
Originally Posted By: sciphi
I'd up the air pressure. 30 PSI is fine for skinny, tall OEM tires, not low-profile 17's.

Also, how heavy are the new wheels? Some aftermarket wheels are very heavy, while others are light.


Although some are probably going to roll their eyes at me for saying this, but it has been well-established on the prius forums that you will lose approx 10% in fuel economy when moving from the 195/65-15 tires to the 215/45-17 tires on the Gen III Prius. The agreed explanation for this phenomenon is that the wider contact patch increases rolling resistance.

Also, the Prius 5, which comes with the 215/45-17 tires, specs 33F/32R for tire pressure, whereas the Prius Two, Three and Four all specify 35F/33R. At least for the Prius, the larger tires must have extra load carrying capacity which allows lower tire pressures to be used.



Thats a great point. I ran 215-45-17's last year with no noticeable mpg loss but the tires were just about finished. Problem with the 215's is that my rims are 7.5 wide and the sidewalls were not flush so i upped them to 225 so they would be flush. My guess is the newness of the tires, contact patch, weight, and pressure. I set fronts and back to 38 psi and will be keeping an eye on it. Will probably drop the backs to 34 or so and leave fronts at 38. Will post my results.

 

[surfstar]

Originally Posted By: The Critic

Although some are probably going to roll their eyes at me for saying this, but it has been well-established on the prius forums that you will lose approx 10% in fuel economy when moving from the 195/65-15 tires to the 215/45-17 tires on the Gen III Prius. The agreed explanation for this phenomenon is that the wider contact patch increases rolling resistance.


I thought I read something from CapriRacer, that RR does NOT increase with tire width. MPG loss could be due to aerodynamics and heavier mass further from the hub center affecting acceleration.
Lower profile tires are also more likely to have stickier rubber and poor RR.

 

[threeputtpar]

Originally Posted By: Rolla07
Originally Posted By: Clevy
You have added weight,and rolling resistance if wider however I suspect the diameter of the outside of the tire hasn't changed much.
So you put 17" rims on a corolla.
How about drag radials up front for track days,maybe some under car lighting,neon perhaps.
And some blue light strips for the floor. Ballin"


Sure, make the assumption that because I put 17 inch rims on a corolla that I am trying to mod it. Sorry you never heard of putting mags on a car to make it look better. Everything else is stock and its purely because it looks better than [censored] stock 15 inch rims/tires. Dont judge people.


I agree that the judgemental comments should be kept to themselves, but for those of us who don't drive this particular car and only know of the Corolla's reputation as an economy car, the thought of it sporting 17s is kind of puzzling at first.

In their defense, you are asking why you economy car is now not getting the fuel economy you bought it for.

 

[Quattro Pete]

Originally Posted By: Quest
@OP:

Your problem mainly lies on the rolling resistance of your new tires.

In addition, brand new tires with full tread will have higher rolling resistance than the same tires that have been worn out. The difference can be as much as 20%, although the affect on MPG won't be nearly as high.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=177&

 

[Quattro Pete]

Originally Posted By: Rolla07
Originally Posted By: JHZR2
Originally Posted By: Silverado12
Did you get your speedometer recalibrated? That would make a big difference.


+1.

I dont get why someone would put 17" wheels on an econobox.



Ughhh because it looks better???

You could have achieved the same looks if you went with narrower 17" rims and 205/50/17 tires. This would have reduced rotational mass of both rims and tires and would not have affected your MPG as much. But I'm not sure if 205/50/17 tires would have sufficient load rating for your car.