Tire size and diff ratio questions

[matty21]

Stock is 245/75 R17 and I have a 3:73 diff. If I go to a 8" lift with 37x13.50x24 toyo tires will it act like I have a 3:55 diff or close too it or how does that calculate? I know it will will affect my speedometer but I'm looking for numbers on how it will act for towing ect. Thanks guys

["Stroker 8"]

Watch out for nosebleeds up there! Seriously, I don't have clue Bud as I have not gone down this path as of now, good luck.

[AlbertaStroker]

Matty. Check this website. You can plug and play the gear ratios and tire heights and see if it's in the recommended RPM range. Calculators

I'm running 3:55s with 37x13.50s. Towing an enclosed trailer of about 7000lbs at 105km/h my RPM is roughly 1400-1500. Fuel mileage of about 11mpg. All hand calculated from Vegreville AB driving the Yellowhead to Valemount BC. Im sure it's the mountain driving that really kills mileage

[matty21]

At 100 km I'm running around 1850-1900 rpm with the stock wheels, I'm suRe that will drop with bigger tires, less revs per mile . I'm guessing

[Bryce18]

Originally Posted by matty21

At 100 km I'm running around 1850-1900 rpm with the stock wheels, I'm suRe that will drop with bigger tires, less revs per mile . I'm guessing

Hey Matty, i believe with 37's you should be about 1650-1750rpms. i may be wrong but i think that will be close.

[Stroken49s]

Axle Ratio - B&C Offroad

I have always used this site for my gear ratio questions, but If I am correct, your stock is a 31.5" and going to a 37" It will be like having 3.18 gear ratio

[matty21]

Thanks guys

[AlbertaStroker]

So when you doin the Lift Matty?? Once it's done we'll have to meet up for a beer and take some pics of our black beauties together haha

[TX_TRU_STUD]

stupid question but what does the RPM "you should be at" mean? I assume for optimal driving MPG's...

I had 255's on my silverado then went to 285's and the rear diff gear ratio kills me on gas. Always wondered what I should have done to fix it. Figured you guys would know.

[matty21]

Originally Posted by AlbertaStroker

So when you doin the Lift Matty?? Once it's done we'll have to meet up for a beer and take some pics of our black beauties together haha

Sometime soon, that would be cool!

Originally Posted by TX_TRU_STUD

stupid question but what does the RPM "you should be at" mean? I assume for optimal driving MPG's...

I had 255's on my silverado then went to 285's and the rear diff gear ratio kills me on gas. Always wondered what I should have done to fix it. Figured you guys would know.

255 to 285's that's just a Width change that wont do anything but add weight, it's the profile that will change the ratio, maybe because it was a gm. Lol and a gasser.