Hi, I have a complete set of 3.07 rears I hope to swap into a future RC/ Cummins conversion project. I plan to use a nv4500 or getbag if I can find one with no issues. Anyways, the RC will more than likely never tow as my other trucks would take up the duty. This is strickly a DD project. With that being said I am wanting to use a 35" tire. Can anyone tell me if that is to high of a ratio to use such a large tire? My RC will never go off road but will be the primarary driver in the snow as well as the summer. I have a pair of complete 3.54 rears as well. But I thought for fuel economy the 3.07's would be better. Any helpful info is appreciated.

 

3.07 gears
1000 rpm 44mph
1500 rpm 66mph
2000 rpm 88mph
2500 rpm 110mph
3000 rpm 132mph
3500 rpm 154mph
3.54 gears
1000 rpm 38mph
1500 rpm 57mph
2000 rpm 76mph
2500 rpm 94mph
3000 rpm 114mph
3500 rpm 134mph
Just to give you an idea where the engine will be at a given speed.

 

are these speeds in direct or od?

 

Those are the speeds in od. They may be a little off because I thought you were running a getrag but I was wrong you have a nv4500. The od ratio in the nv4500 is .73 and the rag od ratio is .77. They are close but not perfect.

 

Thanks for the info nut.
But what I meant was will the 285 tires I am wanting to run be more than I can use with that ratio? I love the low RPM's to run 70mph or so. I could have sworn that I read before people telling another member that anything over 265's would require 3.54's at the least. Anyone remember that? Thanks

 

If you arent towing then the low rpms will just save you fuel.

 

If not just shift down. There isn't a huge step between 4th and 5th. If it were me, and I had a set of both axles, I would try both ratios. I know it's a little screwing around to swap out axles, but so is a RC cummins conversion. I have heard of guys running 35" tires with a getrag and 3.07 gears AND TOWING. There was a post on here a few years ago and there were a few guys running that way. They all loved it.

Off-topic, but not. the HO 24 valve VP 44 trucks came with a 6-speed NV-5600 (higher overdrive gear then the 4500) and a 3.54 ratio. The 3rd gens with that tranny have a 3.73 ratio. the 2nd gen HO trucks got way better mileage than the standard output with a 4500.

 

Thanks guys, I am not much on dialing in ratio's . But I do have both sets of complete axles. I would love to swap in a auto behind the cummins for the simple reasons of city driving, never towing (never had good luck towing with an auto) and the fact that no matter how many times I have tried to show my fiance how to drive a stick she still wont push the darn clutch when she is stopping. All well , shes pretty to look at and makes good sammiches

 

lol!!!

 

Sorry do you have 35's or 285's? 285's are only 33". I Run really heavy (military) 36's with an auto and 3.54's and it does it just fine so a stick with lighter, smaller tires but more gear will be great for a daily.

 

Sorry, I do have 285 bfg all-terrains.

 

Well then that changes all the numbers that I posted.

 

I have talked to guys running 38's on 3:54's no problemo....running the 285 on the higher gear ratio shouldn't be an issue. The cummins will push most tires without much change as far as I have noticed. I have 285's on my rig right now as well. If you are lifting your cummcharger, I'd go bigger. Mine look a little small with a 4", but not bad, just heads up. Love your big red tractor. Not to switch subjects, but what model # is that front bumper? Is it a ranch hand? I have been on their site but didn't notice a model for the 1rst gen. Thanks.

 

I had a buddy (fabricator) copy a design and make it for me. Not sure what brand it was. Thanks for the compliments. I plan to get it painted next year. I like the red on black look.