Best tire size for BJ's 4" lift - Daily Driver

[asahilover]

My Wag is a daily driver and with 3:31's it turns some high RPM's with the stock tires.

I'm wondering whether to go 31 10.5's or 32's. I'd rather go 31's but I don't want it to look like the tires are too small. Also I'd like to turn some lower RPM's at highway speeds for better MPG. There's my dilemna. Anyone got any info or pics of a rig with a similar set-up?

Yes, my driver side springs are sagging, and the gas gauge doesn't work, and the tailgate window doesn't work. Sound familiar? Think I'll take a cutting torch to it and make it a convertible.

Thanks

[carrotman]

What do you consider high RPM's? 2,500 RPM @ 60MPH? There is a formula where you can plug in RPM, MPH, gear ratio, and tire size and change each one. Might be in the tech pages. The first thing would be to see where the torque peak is for your engine and where it will be with a new cam. At 60 MPH, you will want the RPM's to be below the peak, but not by too much. Your gear ratio and MPH is constant, but you can change the tire diameter and see what RPM is produced.

[SpruceMoose]

31s look really good with a 4" lift. but dont expect much in the way of mpg improvement.

sm.

[millertime]

id invest in a sawzall instead of using the torch. Seems like you would end up spending alot less time cleaning edges that way.

[carrotman]

On my 76, I have 31's with a 3.54 axle ratio. At 60 MPH, the engine is turning around 2,250 RPM. Just right for me. With my T18, I know that my trans is in fourth gear and not slipping. If you have an auto, maybe it's not shifting into third or it's slipping. On my six-speed motorcycle, 60 MPH is around 4,000 RPM. Right where the meat of the powerband starts.