MPG between 33 and 35 inch tires?

[rob845]

Ok I got my 3" blocks in and did a TT on the front. Rear diff is the 3.75LSD The current tires are 285/70/17 and I am thinking about moving to 315/70/17 but am a bit unsure about the impact on highway MPG.

I am not sure if the PO had any computer tune done to correct for the tire size but at 50mph indicated on gps the speedo is correct.

Am I correct in assuming that MPG should increase a bit on long HWY runs due to bigger tires ( bigger circle @ same RPMs moving further )

 

[SOLISIMO]

I hope you mean 50mph and not 50mpg.

 

[rob845]

LOL didn't catch that, its fixed..

 

[tonydiv]

Unfortunately, it is much more work for the motor to turn those bigger tires, so mileage will be less on the highway and in town. If you install new gears, you can get back a few of those mgps, but not all of them (Although if all your trips are downhill.....)

 

[rob845]

Ya, I'm just wondering what the diff would be between the two. I need to get tires this week and Just don't know which size to go with...

 

[SOLISIMO]

I would go with 35s bc youll always wanna go bigger

 

[nvycrmn]

i agree with sol. you are going to lose mpg either way. i get about 11 on the highway with my 35's, but i need a tuneup really bad...for me, i wish i would have waited to get these 35's cuz now i want to upgrade to 37's...

 

[Thermo]

Using a guestimate, you can plan on loosing about 1 mpg going from 33's to 35's after factoring in the error for the tires. So, is that an acceptable mileage loss for you? But, like was mentioned, you are going to loose some on the highway and a lot in town (can never really get the truck up into the power band unless you get on it).

 

[panda24619]

but hey bigger tires will make you look cooler! haha so get some 34s or 35s. they will look good. and then if your down hill youll get better mileage than before, but... getting on it is where you lose your mpg.

 

[rob845]

If it's 1-2 mpg then that is no biggie. And for in town I am on my motorcycle 80% of the time anyway. But I would like to know that I can still get to Austin and back in a day on 1 tank. I would usually end the day on that trip with just over 1/4 tank left...

 

[tonydiv]

I would go with 35s bc youll always wanna go bigger

Yea, look through the forum, you'll never see the words "I wish I got smaller tires"

 

[walnuts4x4]

holy cow... I have to agree with panda...lol... but for the little bit of mileage loss the better looks of 35s are well worth it...