Firestone transforce ht tires

[Black Jack Davey]

On 12/10/2017 at 7:59 AM, rocnrol said:

Bigger tires are going to hit your mileage, regardless. That's the trade off.

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By "bigger",  do you mean wider?, taller?, or both? What about tread? 

[rocnrol]

By "bigger",  do you mean wider?, taller?, or both? What about tread? 

Height will be the single biggest determinener, as that is what is directly having an effect on your overall gear ratio. A low gear (numerically higher, IE a 4.10 is a lower gear than 3.73) will allow for more effective transferring of torque, especially from a stop, but will increase the engine rpm at highway speed.

Taller gears reduce the ability to transfer torque, especially from a stop, but will result in lower rpm at highway speed.

If you're asking yourself right now, "wait, so with a taller tire, won't my over all gear ratio get taller? And shouldn't my engine rpms go down? And shouldn't that actually improve my milage? " then yeah, one would think, and for the most part you're right, but is the resulting rpm in the engines power band? Or is your foot stuffed right to the floor just to keep up with traffic. Typically it's the latter, which results in the drop in milage. A wider tire adds to the issue by having a larger footprint, which increase the rolling friction. Tread would have the least amount of effect.

As I've said though, a 34" to 35" tire is not a massive change, and at most will result in a 1-2 mpg change in milage, while, more importantly, look cool AF[emoji41]

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[rocnrol]

Okay,  I've found 315/70 r17's that would look good.  Would these rub on my stock 2015 2500hd 4x4? 
Limited selection in that size.  Ko2's are my fave, but not this time around.  I don't want to sacrifice the  mpg. In that size it's Bridgestone revo, conti terrain contact a/t,  pro comp at sport, Cooper at3 or atp.  No michelins that size, otherwise I'd get michelins. Maybe the Michelin at2 in a 285/70 r17 would be more sensible? 
Assuming I got 315/75 r17's in a tamer tread than ko2's, how much effect would those have on mpg compared to stock transforce ht 245/75 r17's? 
Will  these tires be a chick  magnet for this old geezer? 

Be about 1-2 mpg hit. They will rub slightly at full lock.

Here's mine with 305 / 70 / 18's, and a comparison chart

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[Black Jack Davey]

Nice looking truck! That size comparison calculator is great. Just going from a 245/75/17 to a 285/75/17 looks a lot different. Assuming Michelin at tread pattern (not very aggressive) how much fuel economy do you think I'd lose going from 245's to 285's?

[rocnrol]

Nice looking truck! That size comparison calculator is great. Just going from a 245/75/17 to a 285/75/17 looks a lot different. Assuming Michelin at tread pattern (not very aggressive) how much fuel economy do you think I'd lose going from 245's to 285's?

Thanks Black Jack!

That's not a very aggressive jump in size, I doubt you'd notice much at all in milage.

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[Big Whiskey]

If you're planning to keep your stock wheels, I'd recommend 285/75/17's. They'll just barely clear on a stock truck, and will easily clear with a few torsion bar cranks. Pics in my build thread of that size before and after the level/wheels.