Axle Gearing Help?

[dodgeboy94]

My car goes 80 mph. with 30 inch tires, what would my rear end ratios have to be to keep it going 80 mph. with 48 inch tires? Anything can help. Thanks, Tim.

 

[BRUTUS_T_HOG]

lol wut? a ramcharger? you post makes little sense

the bigger tires you have the lower gear ratio you need in the FRONT AND REAR.

i assume you are only asking about the speedometer? figure out what speedometer gear in the transmission you need and change that to compensate for tire size/axle ratio changes

 

[1badexplorer]

I hope that you don't plan or swapping gears in the same axles you run 30s on and bolting 48s on. There would be alot of other upgrades needed before you do that such as hopefully bigger axles, brakes, and upgraded steering.

 

[RangerSVT]

Not to mention you would need a motor upgrade as well...come to think of it I don't believe they make a 48" tire to handle that kind of speed, much less one that has been at that speed...
SVT

 

[dodgeboy94]

My car is a 1969 Dodge Charger I am converting to 4x4. I am not making it to beat the hell out of. I am putting bigger tires on for show. I am going to run Dana 60's front and rear. The tires are 1400x20 Michelin Military tires that are 48" high, rated highway legal and will handle road driving. I am just wandering what kind of gears I will have to run in the axles to keep from changing the speedometer gear. I want only to change the axle gearing, so it will not go too fast for it to handle. With 4:10's it would go 128 mph. with the 48's, and that is too fast for comfort. The motor will have no problem turning them, it is pushing around 400-450 Hp. That is plenty for show. I will be glad to show some pictures when it is completly finished.

 

[RangerSVT]

Those tires should be closer to 52 inches IIRC when I use to refurbish the military tankers (HEMMTT), and those tires ran on 2.5 ton rockwells, which ran a 6.72 ratio in those axles. I think the lowest gear available in the D60 was 5.89, but I could be wrong...I'd run the lowest gear you could get for what you are wanting to do, but thats my opinion...
SVT

 

[1badexplorer]

If he is running a low pinion dodge/ gm front he can buy as low as 7.17 gears. If high pinion 5.38 is the lowest. I think them michelin tires come in both 48" & 52" tall sizes.