2nd Gen Non-Engine/Transmission Tire size vs MPG

[rmrc]

I currently have the stock 245's with 354 gears and am getting excellent mpg numbers. I was considering going to a larger tire size, but I've heard that usually results in less miles per gallon. It this true?



Maxinum fuel economy is my main concern.

 

[stownsend]

You're not going to get less MPG, but it will appear that you are. That is because the larger diameter tires will throw off the speedometer calibration.



As long as this doesn't bug you, jump in. If it does bug you, you can spend the $ to get it re-calibrated, or there are existing calculations that you can use to help you figure out the true MPG. I don't know where those calculations are right now, but somebody will point you to them.





Steve

 

[jkern]

YOU WILL GET LESS...

trust me on this you will get less fuel milage. i had 245'x75s with 3. 54 gears and then went to 33 inch tires. the bigger tires are heavier and take more HP to turn because they have more rolling resistance. i went from 18 MPG to about 16. 5 and that is corrected for the tire size! my brother had the same results on his truck going from 265x75's to 33 inch tires.

 

[KL]

Jeremy, when you went to the 33 inch tall tires did you also get wider tires or did you stay with the same width? A wider tire could increase the rolling resistance. KL

 

[rmrc]

I was only considering going from 245's to 265's. Would there be any benefit to going one size higher?

 

[JJW_ND]

235/85R16E

As tall as 265's but slight narrower. Same rating rating as 245's. Will not hurt mpgs and should help. They are general as cheap or cheaper then 245s.



jjw

ND

 

[RKohn]

Your Mileage May Vary....

taller & skinny is better than taller & fat . Taller & fatter is also heavier. Rolling mass adds up.

 

[rmrc]

235/85R16E

Is the handling / stability and traction just as good withn the 235/85R16E's as the 245's?

 

[illflem]

Larger tires will net you better mpg with highway miles, less with stop and go. Larger tires take more power to get rolling but once you're up to speed larger tires require fewer rpms for the same mph as a small tire. This is assuming width is the same.

 

[lmills]

went to 285/75's and picked up fuel mileage. I have the 4. 10's and was getting about 16. 5 mpg. Now I get 18 mpg. This is 90% highway driving

 

[Tardog]

Illflem speaks the truth. I do a lot of highway driving and went down from a 285 to a 265 and lost 1mpg. but no increase in power. It's because the lower rpms the better the mpg.

Cheers,

 

[bluequad]

I finally figured out how the tire size calculations work. I have stock 265 75R16. I thought going to 275 70R16 would WIDEN the tire but keep the stock height. WRONG!! I need to find a 285 70 R16 which they don't make. The 285 75R16 will be taller and will mess up my speedo, but the 275's referenced above are going to be shorter. ! So either way, it'll be off!!



I suppose 285 75's are going to be the way to go.



Anyone want to buy a set of Brand new BFG AT's (275 70 R16's)with less than 200 miles?



Steve

 

[Dave Zuber]

RMRC,



You have fairly tall gearing now. Depending on how fast you drive, you may get better. If you drive 55mph. A taller tire might put the engine below 1500 rpm and cause some stress on the transmission and get no power. If you are moving 65+, I'd go for it.



Your current 245-70x16 are about 29. 5" diameter. There is a 255-85x16 tires in a D rating. Tall and skinny, but not good for heavy hauling. About 32. 5" diameter if I remember right.



If you pull heavy, it might get 3rd gear higher and into a more useable range. Overdrive would become useless though.



I don't think the weight of the tires will make that much differance on a truck over 7000#. It does make a differance on Toyota's.



What the hell, if you don't like it, change it in 50k miles.