Best tire width?
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I would stick to a narrow tire. I've never heard of a 31x8R15, so they must not be too common. Do you need something 31" tall? I like running a 235/75-15 because they are common and cheap, but they're only about 29" tall.
Post Fiend
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From: Louisiana
What gear ratio do you have, and how fast do you normally travel(70?55?).
I ran 235/75R15s on my 77 F-100 302 C4 and I was getting 16 mpg with 3.50 gears
I swaped on some 31x10.50R15s, and it went down to a consistant 14 mpg, so with gas prices, I'm back down to the 235/75R15s.
I'm like you, I think the 31s look great, and personally I hate the look of the small tires I'm running on stock wheels and hub caps, but for 2 extra miles per gallon, I'll keep them on.
I ran 235/75R15s on my 77 F-100 302 C4 and I was getting 16 mpg with 3.50 gears
I swaped on some 31x10.50R15s, and it went down to a consistant 14 mpg, so with gas prices, I'm back down to the 235/75R15s.
I'm like you, I think the 31s look great, and personally I hate the look of the small tires I'm running on stock wheels and hub caps, but for 2 extra miles per gallon, I'll keep them on.
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So what would 245/75R 15 tires do, improve economy a little or hurt it a little compared to 235's?
This is on a '75 F-250 Supercab, 390, 3.54 rear.
Ray Mac
This is on a '75 F-250 Supercab, 390, 3.54 rear.
Ray Mac
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Post Fiend
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From: Louisiana
If you drive on the hwy alot, then yes your RPMs will be lower causing better MPG, but if you strickly drive in town(like I do), you have better mileage with 235s(just for the reason that you will have the most take off power with that combination, and that's what you need in city driveing).
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A taller/larger tire will have more rotational mass to get moving and keep moving. It takes more work to do this, and according to physics, work isn't free. More work = more gas. Taller than stock tires on a vehicle will get worse mpg on the highway and so will wider than stock tires.
Last edited by 460; Jul 11, 2006 at 05:43 AM.
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Wider yes, talller no, beacuse they will lower RPM's preportionally to their size.
But that's a moot point, i'm looking for sizes and what works and what's available and what people are running.
But that's a moot point, i'm looking for sizes and what works and what's available and what people are running.
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And then the engine has to work harder, thus lowering mpg. The taller tire is a larger "lever" than needs moved. It takes more force to move this larger lever.
I'm telling you what doesn't work to increase mpg, and it's a taller tire. The best tire size to me on a dialy driver would be the one that gets the best mpg.
I wonder why the econo-cars that get best mpg (50-60 mpg) have such short tires? It seems like if a taller tire = better mpg, they would all run some tall, thin 44's?
http://answers.yahoo.com/question/in...=1006041724307
I'm telling you what doesn't work to increase mpg, and it's a taller tire. The best tire size to me on a dialy driver would be the one that gets the best mpg.
I wonder why the econo-cars that get best mpg (50-60 mpg) have such short tires? It seems like if a taller tire = better mpg, they would all run some tall, thin 44's?
http://answers.yahoo.com/question/in...=1006041724307
Post Fiend
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From: Louisiana
Like 460 said, a taller tire is harder to start rolling causing bad mileage, but like you said it will lower RPMs on the highway, but for instance when I had 3.50 gears and 36s, I would guzzle gas getting up to 70 mph, but once I got there, my rpms would be like 1,500(which wouldn't off set all the gas used to get up to 70 mph), so taller tires do = less mileage also.