Remedial Question

[drohweder]

I'll put that up in advance as you all will surely make me feel that way with the answer to this question:

With the diff gearing which ones are faster or slower (speed). Is a 4.11 faster (better for highway) or 3.70? Could I assume that a lower ratio (3.70??) would be better if your running larger tires and using the truck mostly offroad? Thanks for the helping a naive non-mechanical type out

 

[2mbb]

I think you got it backwards. A 4.11:1 will spin the wheels less for each engine rpm than the 3.70:1. 4.11 is better for larger tires off road. 3.7 is better for highway travel if you want low engine rpm's at speed.

 

[drohweder]

That makes sense. So with a 3.70 set up at what point do you start loosing power with increasing tire size? (what size tire is too big).

 

[Romer]

Don't know the answer to your question, but the information you need is probably on TLCAs site at the following link:

http://www.tlca.org/trails/techxchg/rpmtbls/index.html

 

[Landpimp]

IMOP 33x12.5's start sucking the life out of a good running 2F, w/3.70's. I have NO issues with my 82 fj40 2F smoged, 3.70's and 33x.9.5......damn thing has lots of balls left. 31x10.5 is an all around good size. 35s and 3.70's is not alot of fun.

a few set up I have and what I think,

82 fj40, 2f, 3.70 and 33x9.5 GREAT, couldn't ask or want any better for my use, run 70mph all day long

86 fj60 2f, 4.10 and 33x10.5 perfect combo, on better would be a 5 speed

67 fj45, 2f 3 speed, 4.10's 35x12.5, not bad but not perfect, the 3 speed is the biggest issue, 1st sucks. 33x10.5 would have been better IMOP, but will do 80mph+, sucks starting on a steep hill.

64 fj45LV, stock F, 3 speed, 4.10's, 28's tall tires, great around town.....top end is limited to 65mph, still good power on hills, no need to drop to 2nd. I think 33x9.5 would be a good match on this.

90 fj62, stock, 4.10, 33x9.5, really a nice combo, no problem with power, just right.

width has almost as much effect has height, a 33x9.5 and 33x12.5 are not the same, 12.5 just sucks more power.

That makes sense. So with a 3.70 set up at what point do you start loosing power with increasing tire size? (what size tire is too big).

 

[HI^C]

this has to do a very large part with what engine you run, next is what trans, varies greatly between vehicles and different drivers.

what are you looking for? highway cruiser, a off road only, on/off road, etc... Then if you plan on towing with it or not?

 

[jesterb]

A good rule of thumb is to deduct .10 from your gear ratio for every 1" you increase your tire size. So if you had stock 3.70 gears and 29" tires and wanted to go to 33"s you would need to swap in 4.10 ring and pinions to bring you back to stock.

 

[78 One owner]

That makes sense. So with a 3.70 set up at what point do you start loosing power with increasing tire size? (what size tire is too big).

Try this link. You can answer your own questions:http://www.ringpinion.com/calculators/calculatorsind.html

 

[mancinator]

402ci+sm420+3.70 diffs+35mtrs=2000 rpm on the highway and im passing people in 60 zones