Tire size... mileage

[gr8shot]

Looking for new rubber. I have the tires picked out.. Firestone Precision Touring. Read a ton of great reviews and they're priced right. My question is size for the best mileage...

 

I know wider equals worse mileage. 225/60/16 was stock on my cutlass, it has 215/60/16 on it now and my best tank of fuel has been 28.9mpg. Would I be best off staying with this size? Its both narrower and shorter than the stock tire. Or would I be better off with something closer to stock height which would be 215/65/16...? Or do you guys think that going even narrower to a 205 size be best for mileage?

 

I don't care about looks. All I care about is mileage, and good grip in the wet and snow since I drive 120 miles a day round trip all hiway for work. I know most any tire will have adequate dry performance for me. I make like 4 turns and I'm at work. Its basically a long straight shot for me so cornering doesn't matter.

 

So what are your thoughts? Stock height or shorter for best mileage and 215 or 205 for best mileage?

 

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[RobertISaar]

unless you want your odmometer and speedometer incorrect, and by effect, calculated fuel economy as well, stick with a size that is the correct height. having a shorter tire will result in the odometer ticking over faster, meaning you'll calculate out a better MPG than what you're actually achieving.

 

you could have the tire size corrected in the tune, and that would solve that issue.

[gr8shot]

I'm not worried too much about the speedometer and odo. I can compensate for those in my mileage calculations. I'm just looking for what will get the best mileage. Or if it doesn't make any difference ill stick with close to stock height.

 

On my duramax goin from stock sized 245/75/16 to a much better looking, taller and wider 285/75/16 was about a 2mpg drop. And i did compensate for the speedo when i tuned it . I don't drive it much so its not as big of a deal. But with the car I'm just after whatever will get me the best mileage.

 

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[BXX]

Want better mileage? Ditch the Precision Tourings (used to be Affinity Touring) and toss on a Bridgestone Ecopia series tire. I believe the EP422 would be in that size.

 

The Precision Touring are the lowest tire in the Firestone line FYI. Decent, but not the best. Don't be fooled by the treadlife warrenty on them, you'll prolly expect to see 40K out of them.

 

Don't get them from Walmart, those arent a real Firestone tire..

 

Try to find a local Firestone, they might still have the Affinity Touring in your size which will be deeply discounted. Affinity Touring and Precision Touring are the same time, different name. Don't ask me why, cause even my tire manager has no clue as to why the change.

[gr8shot]

My dad has a set of the precision touring tires and they've been great. No affect on mileage and above average wet and snow traction without being noisy. And they're wearing pretty good IMO.

 

But anywho I'm more worried if size plays as big of a role on these cars as it does on my dmax. Nobody piping up and saying yes leads me to believe it doesn't matter much.

 

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[RobertISaar]

let's see.... on the same set of wheels, i've ran 205/65R15s, 205/70R15s, 205/75R15s, 215/70R15s and the monster of the group: 215/75R15s.

 

no significant fuel economy difference was noted.

[Galaxie500XL]

X2...Rolling resistance is more of an issue than the tire size...unless you're going to radically larger stuff, like putting 22" wheels on the car..

 

 

Stick with the stock size, if you're worried about mileage, find low rolling resistance tires..but, keep in mind, about the most you'll gain (depending on whom you believe) is 1-4% improvement....

 

 

But, keep in mind, if 28.9 MPG represents your best mileage ever, 1% improvement represents a .289 mpg improvement, 4% represents a 1.156 mpg improvement.

 

Or, thinking about it another way a W with a 15-gallon tank, a 1% improvement means you'll go 4.3 miles further on a tank, at 4%, 17 miles.

 

 

 

 

let's see.... on the same set of wheels, i've ran 205/65R15s, 205/70R15s, 205/75R15s, 215/70R15s and the monster of the group: 215/75R15s.

 

no significant fuel economy difference was noted.

Edited April 3, 2012 by Galaxie500XL

[gr8shot]

Thanks guys. That's what I was hoping to hear. I was worried that it'd be a big deal like on my truck. Ill just keep em about stock size and not worry too much about it.

 

I understand the rolling resistance concept and how weight per wheel and tire has an affect and what not. I learned that lesson when I put heavy ass 20" wheels with really wide 305/50/20's on my last dmax. They looked killer but not only did the truck feel slower but it got worse mileage by quite a bit. When I'd switch back to a lighter wheel and tire combo for winter my mileage would go up for about a month til the stations switched to winter diesel then it'd go back down to about the same as with the 20's.

 

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