Hello everyone,

I'm a new member and I have just purchased a set of BFG 285/70/17 tires for my screw. I may start off with my current gearing of 3.55 but i'm thinking of going to 4.10. I was told this will make much more rear axle noise and keep me from running over 75mph. Is this true? I expected the new tire and axle setup would get me somewhere around the 3.73 diff which I thought would be perfect. What do you think?

Thanks for your help!

 

Welcome ! You can get more noise in lower gears (higher numerically). If you buy a quality gear set and the installation is done correctly, they're generally acceptable. Stay away from the person that told you the 75mph BS. You would only be going 2200rpms at 75mph in OD. The 4.10s with that tire size will not be far from your original performance. Let us know what your original tire size was and what your performance/mileage expectations are.

 

My current tire size is Cooper LT 265/70/17. I'm currently getting around 16mpg with these tires.

Thanks for the help!

 

One other thing, i do some highway driving through the mountains and i'm wondering how much gear searching this new set up will cause? This is with the 285/75/17 BFG A/T tires and the 3.55 rear diff.

Thanks,

 

You're welcome ! Those are pretty tall factory tires. The new tires being about 1" taller won't make much difference. A 3.73 gear would get you close to original performance. I agree, a 4.10 gear sounds like a better all around ratio. With the new tires and 4.10s, at 70mph in OD, you should be running under 2100rpms. If your mountain trip causes your truck to shift out of OD repetitively, turn the OD off.

 

Has anyone had bad experiences with gear changes. Since I have a 4x4 i'll have to do both front and back. Also, i'm looking for a better rear limited slip or locker. Is this the time to upgrade this as well?

I've talked to 3 places and everyone has told me NOT to change gears to 3.73 or 4.10 because they will be louder and i will not be happy with them....

Your thoughts please!

 

Only exhaust noise (b/c of higher RPM) @ highway speeds and poorer gas mileage.

 

as stated earlier, get a good set of gears this will def help. lower gears tend to talk a little but with exhaust noise, road noise, traffiic, radio volume you probly not hear it too much also you def need to redo your speedo with a gear swap 3.55 to 4.10 you'll see a big diff on the dash.




good luck