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245 70 16

3K views 8 replies 4 participants last post by  dirtwarrior  
#1 ·
I have 3.73 gears in my truck. I haul very little and around here just gentle hills.

I have a chance to get a great deal on new 245 70 16 tires. They are about 2" taller than the stock tires

They gearing will essentially go to 3.36. will I gain or lose MPG with this set up?
 
#3 ·
And a loaded question.
How do you drive?
Are you in stop and go traffic a lot?
What is your average speed when driving?
What compound and tread patterns do the new tires have?

The real questions here should be...
will these fit without rubbing?
Do you like the way your truck looks with them on it?


taller tires will make your vehicle more of a aerodynamic brick to push, but at low speeds that is irrelevant.

Taller tires will also make accelerating from a stop more costly fuel wise.
But they will also lower your RPM at speeds.
Taller tires will also effect your speedo readings so your going to go farter and faster than recorded.

put them on the truck and let us know what you think.
 
#4 ·
I drive very conservative almost like a granny.
The tread pattern is a street all season tire.
Most of my driving will be in farm land with very little city.
I do have a programmer to adjust my speed.
As far as looks and rubbing I am not sure.

Thanks for the answer and the questions. I did not think of them.
 
#5 ·
More than likely your mileage will decrease, largely because these tires are a lot heavier than your old ones. Check the load rating and weight of the tire and compare to what you have.

Also, your braking will take a hit due to the increased diameter and rotating mass.

The problem with these trucks is that they don't have much torque - so running at a lower RPM on the hghway can make them lug a bit and downshift often.

I had 3.73 gears - I went to a 32'' tire and mileage, braking, and drivability suffered. I upgraded to 2009+ brakes, and 4.10 gears and it's much better. Interestingly enough my mileage improved with the 4.10 gears.
 
#7 · (Edited)
I've gained mileage, mostly on the highway going to a 29.6" tire from the stock tire on a z85 with 3.73 gears.

went from 235/55/r15 to 265/75/r15. Also went from an all season to all-terrain tire. I contribute the gain in mileage mainly to my driving style, as on highway I set cruise and don't fuss with it much. I dropped under 2k rpm at 65 (roughly 1800 rpm) from ~2100rpm).

City driving, it doesn't help at all, the truck doesn't feel as quick on the butt dyno, and doesn't brake as well either. But i rarely get stuck in stop &go, and most of my city driving is on 25 or 30 mph areas. I average 18-19 mpg combined, and personal best was just north of 22mpg on a road trip to CT and back. I will add that I don't mind the slight loss in performance, the tires perform so much better on everything but a perfectly dry road.
 
#8 ·
WEEEEEE MATH.

ok for fun lets say you get 20mpg all the time.
and lets say these new tires cost you 2 mpg
that means in 40,000miles (a fair guess of how long those tires will last) 40,000/20mpg= 2000gallons
Those new tires will cost you a extra 222 gallons of gas. 40,000/18mpg= 2222gallons of gas.
I pay about 3 bucks a gallon here...so those tires your getting a deal on could cost you a easy 600 bucks.

Hypothetically speaking.
loosing 1 mpg=300 bucks
gaining 1 mpg= +300bucks etc.

Just fun math. I wonder how good the deal was on the tires..

P.S. I have spent more than 600 bucks on tires just because they look good.