Re: [A/S] towing with a jeep-trying again

["Craig Eldridge" <craig_e@xxxxxxxxxxx>]

The rear end ratio is the gearing in the rear differential.  You have a 
pinion gear attached to the driveshaft and a ring gear with more teeth that 
is connected to the rear axle.  Minimum towing gear ratio should be around 
3.73 to 1 and in some vehicles the 4.10 or 4.11 to 1 is better.  The higher 
numerical you go, the more pulling power you have.  Some call it a lower 
rear end ratio rather than a high numerical ratio.

If you marked a spot on the drive shaft that is visible and marked a spot on 
your tire where it meets the ground, the axle will turn approximately 3 and 
3/4 times for every full turn of the rear wheel for the 3.73 rear end ratio. 
  The 4.10 or 4.11 ratio will start a standing load easier than the 3.73 but 
in all cases the engine rpm's are higher and the engine may use more gas on 
the highway.  Notice I said may because it depends on the engine and the 
load.  If the engine is laboring up mountains it could possibly use more gas 
with the 3.73 to 1.  Some of the smaller trucks are using 4.56 to 1 because 
of high reving powerplants.

Another thing to look at is tire size.  If you found a vehicle with 3.73 to 
1 ratio and it pulled the camper fine, if you went to a 1" or 2" taller tire 
you could ruin the towing performance.  I have LT245-75-16 load range E 
tires with the 3.37 to 1 rear end ratio.  I now wish I had gone with the 
4.10 to 1 and then installed taller tires such as LT265-75-16 load range E 
tires.  This would have brought the ratio closer to 3.90 to 1 and given me 
more torque than I now have.

When you look at any vehicle, you should buy one set up for towing from the 
factory.  Some have purchased a vehicle without the towing receiver and a 
3.42 to 1 rear end ratio, added the receiver and been disappointed with the 
performance.  The 3.42 to 1 may be fine with a small boat trailer but even 
my son found that the 3.73 in his current 1/2 ton truck pulled his 
grandfather's boat much better than the 3.42 ratio that it replaced.  Are 
you starting to get the picture or have I just confused you?