Skinny tire question

[Musick17]

If I have 15x7 wheels,what is the skinniest tires I can safely run on them?

Ide prefer to keep the tire height under 30" if possible. I'm going for the whole gas mileage thing while in college. So if anyone knows of any helpful hints let me know. If it helps, I have a 2002 2.3L manual.

Thanks

 

[CountryBoy78]

I am not sure what your stock tire size is but I do know a couple tires sizes that will fit stock 15x7 rims.
235/75/R15, 30/9.50/R15, 31/10.50/R15, and there probably a few others but that is all I can think of now...... The widest I would go on a 15x7 rim is 31/10.50/R15. That is what I have on my 94 Explorer now.

There might be some 70 series that would fit like 205/70/R15....but that is getting pretty small.

 

[strvger]

mine are about the skinniest, 215/85x16 but they are 16 inch wheels. for you, probably the 235/75x15 would be your best choice. they are a little wider than my tires, but never heard of any 15 inch tire with an aspect ratio higher than 75.
oh, and the 30/9.50x15 tires are usually within a half inch of 235/75x15 size. if you get the 'C' or 'D' rated tires, the stiffer sidewalls allow for higher pressures and lower rolling resistance. that also translates into a little rougher ride usually.

 

[Musick17]

Thanks for the input guys.

Im either gonna go with the 30/9.50x15 or 235/75x15.

So the next question. The 30/9.5 is a 30 inch tire and the 235 is about a 26.4 or something. The 30 inch tire is skinnier but also 2 and a half inches taller. Reckon the 30 inch would suck to much power out of my 2.3L compared to the slightly wider 235/75? Or would there even be a noticeable difference?

 

[--weezl--]

i would go to a junk yard and pickup some smaller rims...

 

[strvger]

you're wrong on the tire heights. the 235's are usually less than 1/2 inch shorter than the 30/9.5 tires. most of the "30" inch tires are around 29.5, nearly the same as the 235/75 tires.

 

[Captain Ledd]

i would go to a junk yard and pickup some smaller rims...

Not much tire choices in a 14" rim for our rangers.

you're wrong on the tire heights. the 235's are usually less than 1/2 inch shorter than the 30/9.5 tires. most of the "30" inch tires are around 29.5, nearly the same as the 235/75 tires.

x2 the 235 might be a hair smaller, but not by much.

The only thing you'd need to get at the junkyard, is a 4.10 geared Ranger rear end (if you don't have one already). That'll be plenty strong for a 4 banger, the only reason to go to a Explorer rear end is if you just plain ol' wanted one.

 

[--weezl--]

ok, some people don't seem to know how to read metric sizes... the first number, by it's self only means the width of the tire, that's it... nothing more... the second number, by it's self means absolutely NOTHING! if you know it's a 75 profile tire, it tells you a LITTLE BIT, but without the tread width (235) AND the rim size (14/15) it won't tell you crap about what you WANT to know and the last number, 14-15 usually with an R, is the rim diameter, same as standard tire measurements

like i said, the first number is the width of the tread (footprint, in MM, which are 1/10th of a cm, and there are roughly 2.5cm in an inch, so 235 is 23.5cm or just over 10 inches wide. the second number 75, is an aspect ratio, or rather a percentage, it is per sidewall, it means that the sidewall (rim to tread edge) is 75% of the width of the tread, so in this instance, (235 75 14) you are looking at 7.5" of sidewall, because that's 75% of 10, multiply that by 2, because there are 2 sidewalls, for 15" and add the rim size, 14, for a total of 29" tall, so a 235 75 15 is ROUGHLY 29x10x15, though because 235 is larger than 10" by a little that is off by a bit...

why do you need 14" rims? i'm sure you could find some skinnier rims off of a jeep or something, that would fit, doesn't matter greatly if they are 14" or 18" as long as you get skinny tires to match...

 

[Frank The Tank]

Tires and rims are not the place to go seeking fuel economy.......

Aside from making your truck look gay and blowing money on new tires your not going to see much gains.

Why has no-one mentioned this yet?
Don't push the skinny pedal as hard while you drive and just keep the tires and wheels you have.

Frank

 

[Captain Ledd]

i would go to a junk yard and pickup some smaller rims...

why do you need 14" rims? i'm sure you could find some skinnier rims off of a jeep or something, that would fit, doesn't matter greatly if they are 14" or 18" as long as you get skinny tires to match...

Anything smaller than a 15 inch rim is going to be a passenger car tire. OP says he has 15x7 rims.

Maybe there was an accidental term mix-up? I've typed/said the wrong word a few times.

ok, some people don't seem to know how to read metric sizes... the first number, by it's self only means the width of the tire, that's it... nothing more... the second number, by it's self means absolutely NOTHING! if you know it's a 75 profile tire, it tells you a LITTLE BIT, but without the tread width (235) AND the rim size (14/15) it won't tell you crap about what you WANT to know and the last number, 14-15 usually with an R, is the rim diameter, same as standard tire measurements

like i said, the first number is the width of the tread (footprint, in MM, which are 1/10th of a cm, and there are roughly 2.5cm in an inch, so 235 is 23.5cm or just over 10 inches wide. the second number 75, is an aspect ratio, or rather a percentage, it is per sidewall, it means that the sidewall (rim to tread edge) is 75% of the width of the tread, so in this instance, (235 75 14) you are looking at 7.5" of sidewall, because that's 75% of 10, multiply that by 2, because there are 2 sidewalls, for 15" and add the rim size, 14, for a total of 29" tall, so a 235 75 15 is ROUGHLY 29x10x15, though because 235 is larger than 10" by a little that is off by a bit...

I agree with you, but you need to change some of your 14's to 15's while you're explaining the math.

We all agreed with you that a 235/75R15 is very similar to a 30x9.50R15.

Frank, thank you. +rep

If you goal is mileage, hop on tire rack and see the skinniest tires thay have for the stock tire dimaeter (I.E., the diameter you have now). and that's only if you need new tires, otherwise, don't bother.

 

[TheTopher]

Tires and rims are not the place to go seeking fuel economy.......

Aside from making your truck look gay and blowing money on new tires your not going to see much gains.

Why has no-one mentioned this yet?
Don't push the skinny pedal as hard while you drive and just keep the tires and wheels you have.

Frank

okay, science lesson time.

Adjusting the nut behind the wheel is the #1 way to see an improvement. But even then, that can only take you so far.


As you're driving, your tire will actually deform a little bit to create a flat spot on the road where your traction is at. Lower tire pressure causes this flat spot to be larger, higher pressure will cause it to be smaller, which is why a lot of MPG crazy guys run higher tire pressure.


As you rotate the tire under weight, this flat spot has to transition across and bend the entire tire in order for the vehicle to roll, this is known as "Rolling resistance" A tire half as wide is going to have half the rolling resistance, since it only has half the tread to bend. This is what his goal is, lower rolling resistance.

Now compound this by the fact that skinnier tires are naturally lighter and reduce weight at the most crucial point, at the very edge of the rotational mass of the wheel, you're definitely going to have an improvement in fuel economy.

 

[Frank The Tank]

Marginal* Improvement.

You forgot that part....
Now lets say he just drives modestly and doesn't have to go out and buy new tires and wheels........... how is getting .2mpg more going to pay for itself over the life of the tire????

While he's at it he better shave his radio antenna (reduces drag) throw away the floor mats (excess weight) and use filled bicycle tires because you just cant get any narrower or less drag than that. And because he'd have the goofiest ranger in the world it would save mileage because he'd never want to drive it.

Frank

 

[TheTopher]

Marginal* Improvement.

You forgot that part....
Now lets say he just drives modestly and doesn't have to go out and buy new tires and wheels........... how is getting .2mpg more going to pay for itself over the life of the tire????

Frank

If he's got his driving habbits adjusted as far as they'll go skinnier tires can yield a 1-3mpg improvement, depending on how bad his current tires are.

For all we know, his current tires are already toasted and he's just looking for a more efficient improvement while he's buying tires anyway.

He also mentioned he's after it while in college, there's quite likely a long commute home on the weekends or even a long daily commute involved with this.

 

[doyouquaxu]

always drive the truck downhill, and you'll get great gas milage

 

[strvger]

"Now compound this by the fact that skinnier tires are naturally lighter and reduce weight at the most crucial point, at the very edge of the rotational mass of the wheel, you're definitely going to have an improvement in fuel economy."

sorry Topher, not always true. i'm betting my 215/85x16 load range E tires are heavier than 245/75 or 265/75 tires that can be had in load range C even though my 215's are considerably more narrow.

good to see you here Frank! thought this crazy winter might have swallowed you up!