Math Guru-help on figuring gearing ratio

[CUMMINZ]

I have 07.5 with 68rfe and 3.73 gears with 33.5" tires 19.5s @ 620 revs per mile. Can someone give me my true gear ratio at the ground?

What gear ratio would I need to give me factory 4.10 ratio with these tires?

 

[chet6.7]

These 2 sites may help.http://www.grimmjeeper.com/gears.html











http://www.rocky-road.com/calculator.html

 

[AH64ID]

I have 07.5 with 68rfe and 3.73 gears with 33.5" tires 19.5s @ 620 revs per mile. Can someone give me my true gear ratio at the ground?

What gear ratio would I need to give me factory 4.10 ratio with these tires?

Your true gear ratio is 3.73.... It doesn't change, just the equivalent ratio as compared to stock tires.


Your current setup is like stock tires with 3.59's.

It would take 3.88's to make your 19.5's act like 3.73's with stock tires.

It would take 4.26's to make your 19.5's act like 4.10's with stock tires.

 

[CUMMINZ]

Your true gear ratio is 3.73.... It doesn't change, just the equivalent ratio as compared to stock tires.


Your current setup is like stock tires with 3.59's.

It would take 3.88's to make your 19.5's act like 3.73's with stock tires.

It would take 4.26's to make your 19.5's act like 4.10's with stock tires.

Thanks for the info. I am trying to find a set of 4.30s.

 

[AH64ID]

Thanks for the info. I am trying to find a set of 4.30s.

I doubt you will. 4.10, 4.44 and 4.56 are the choices from what I recall.

I'd like to find a set of 3.90's for my truck....

 

[CUMMINZ]

I doubt you will. 4.10, 4.44 and 4.56 are the choices from what I recall.

I'd like to find a set of 3.90's for my truck....

Are you interested in my 3.73s when I remove them.?

 

[AH64ID]

I have 3.73's.

 

[cerberusiam]

4.30's are available from a couple vendors. http://www.dieselpowerproducts.com/p-8828-nitro-ring-and-pinions-115-aam-solid-axle.aspx

 

[CUMMINZ]

4.30's are available from a couple vendors. http://www.dieselpowerproducts.com/p-8828-nitro-ring-and-pinions-115-aam-solid-axle.aspx

I have already spoken to DDP about 4.30s.

 

[CUMMINZ]

Ordered a set of 4.30 gears for the RAM two days ago from DPP. They are on FedEx today. Local dealer will install tomorrow. Also looking at a BD intercooler.

 

[CUMMINZ]

Ordered a set of 4.30 gears for the RAM two days ago from DPP. They are on FedEx today. Local dealer will install tomorrow. Also looking at a BD intercooler.

Got the gears in and they are doing great. 2000rpm at 70mph.

 

[CUMMINZ]

It has been a while since I gave an update on my 4.30 gear installation and hoping to cure my high EGTs. The 4.30s are doing absolutely great and have worked out much better than first thought. I have been experimenting with my Smarty and due to increasing the Timing setting to #4 and Turbo to #4 it has lowered my EGTs to very good ranges. I wished I would have these gears and Smarty worked out before our OUT West trip last summer.

 

[CUMMINZ]

Here it is May 2019 and we absolutely love these 4.30 gears with the 19.5 tires.

 

[cerberusiam]

FYI, be very careful with added fuel and the timing. Too much timing and you will be doing an HG.

 

[CUMMINZ]

FYI, be very careful with added fuel and the timing. Too much timing and you will be doing an HG.

I'm dumb. What is HG?

 

[cerberusiam]

Head gasket.