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With the 19.5" wheels the tires are commercial, same as you see on gas powred motorhomes. These tiers prety much don't get flats, I had two nails in one of my tires last week, all the way through, an
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Assuming that you were in 6th gear (.73:1). Axle ratio = [(engine rpm) (tire diameter in inches)] / [(mph) (336) (transmission gear ratio)] ? = [(1825 rpm) (33.4")] / [(
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I was just making sure I was using that calculator correctly. I punched in my stock size in both fields and came up with 3:55 which is the ratio of both axles. So my final drive ratio is at 3:55-1 ?
So the truck came with a set of Rickson wheels 19.5" and a set of tires that were less than a year old. I liked the old forged-in-America wheels so I decided ot keep them on the truck.
I have never had one of these trucks befoer this one so I have no comparative baseline on how it "should" run and drive. In LA these trucks are like hen's teeth and I have not found anyone near me that knows much abou them at all. My local dodge dealer is a waste of real estate and every time I've gone there they turn up their nose at my old truck and try to sell me a new truck :-) I couldn't even get a radiotor cap from that palce.
After studdying this issue of tire size, on this website, more closely I decided to take a closer look at my set up as believe there is a fly in the ointment.
Now for the more-fun-with-math part.
So according to Mopar1973Man the goal is to have a Final Drive Ratio that is between 3.55 & 3.73
My truck started its life with a final drive ration of 3.55 (Dana 80 in the rear and Data 60 in the front)
Stock tire size was 235/85-R16
Current tire size is 203 245/70-R19.5
So I have a lift of about .85"
https://tiresize.com/comparison/
Upon running the calculation I now have a paultry effective final drive ratio of 3.41, so far so bad.
https://tiresize.com/gear-ratio-calculator/
Now the question is to should I lower the water or raise the bridge?
I could keep the wheels and change the gearing in the Axels or I can get a set of wheels and tires.
Either solution will cost about the same in the greater LA Area.
So let's say I decided to go the regearing route.
I believe Dana offers 3.73 and 4.1 gearing.
The question is this, if I went the re-gearing route which would be preferable (either 3.73 or 4.1) and why?
Also I have the NV5600 at (0.73:1) and I'm not exactly sure how to add that into my math here or that's even relevant.
Thanks @Mopar1973Man for this article this is super helpful in trying to sort this all out.
Edited by leety