The truck I'm looking at has 4:10 gears and either 305 or 325 ( 34" 35") tires on it . What does this do to the gear ratio and how does it effect performance,economy? I have looked at charts on the web but I don't understand what I'm looking at ?

 

That should be about 10% change, so about 3.6 from 4.10. Someone else may do it exact for you. You need your exact tire diameter not the number on the side.

Cya

 

The actual tire size is 33.7 or 34.61. What does this do to my gear ratio and is it desirable? Most trucks come 3:73 gears and when larger tires are put on then mpg and power suffer. But what happens when larger tires are put on with 4:10 gears? How close does it get it to 3:73?

 

I don't know if this will help or not but someone here on DTR gave me this link. You can play with the different tire sizes and ratios to get the RPM's and compare with stock numbers. http://www.csgnetwork.com/multirpmcalc.html

I was told to use .69 for the OD ratio on an automatic and 1.0 for drive. I am strongly considering putting in 4.10's in place of the 3.73's so that I can get back close to stock gearing with my 35's.

 

Which is better for fuel economy 35" tires with 3:73 gears or 35" tires 4:10 gears?

 

I put 31.5s on my truck during the winter months ( 6). my speedometer is off 10% as measured against my GPS

 

How you use the truck will have as much affect on your average MPG as the tire/gearing combo itself. Higher overall gearing will generally increase MPG running unloaded on the highway. Lower overall gearing will generally increase MPG towing at slower speeds. Higher overall gearing generally hurts MPG during stop-an-go in-town type driving. Lower overall gearing gets better in-town MPG.

Driving style + overall gearing = average MPG

How's that for a nebulous equation?

All things being equal, stick trucks get better MPG and tow better. (flame suit on! )

 

4.10's will be too low on the highway with these trucks and stock tires. Bigger tires will be fine. I run 3.73's with 315/70/17 tires so my ratio is high and I do very little highway driving. Plenty of power even while towing with the higher ratio. The cummins has enough torque that it doesn't seem to affect it a whole lot where with a gasser and big tires with high gears will be a dog. Mileage differences will be small and may actually improve depending on driving style and type.

 

hi guys

i can put 35/12.5/18 on stock truck(no lift)?

thanks for help.

chris

 

hi guys

again,(other dimension) i can make 325 60 18 on stock truck?

anyone have pictures from this combo?with copper stt

 

nobody? have pictures

 

That's a little over a 33" tire, so I doubt you would have any issues with it fitting stock suspension height. It's pretty wide, so I suppose there's a possibility it might start to rub somewhere near full lock, just a guess.

 

my dealer have trucks with stock suspension and 325.
i think that works
http://www.calonder.com/parts.php?shid=69

 

Seems to be a lot of tire guys here so here goes. Will there be any negative results going from 265-70-17E (stock) to 285-70-17D towing 7500lb TT. That's 1inch taller and 1 inch wider than stock, 3.78 gears.

 

From the looks of it on the RPM calculator, you probably wouldn't notice much difference at all. ( Disclaimer, I'm not a tire guy).