What gears

[raiders322]

I have a well maintained 95 1500 4X4 Z71 Automatic running 35's. The motor is original with headers, flowmaster exhuast with no cat, jet stage 1 chip and a K&N system. I am in a debate on the right gears to get for towing a new toy hauler weighing about 7000 loaded. I live in between the Cascade Mountains and Coast range of Oregon and you must climb a hill to have any fun. It's not a daily driver but fuel is not cheap in Oregon. I am debating over 4.88 nd 5.13's. Does anyone have any input.

[pm26]

I have a well maintained 95 1500 4X4 Z71 Automatic running 35's. The motor is original with headers, flowmaster exhuast with no cat, jet stage 1 chip and a K&N system. I am in a debate on the right gears to get for towing a new toy hauler weighing about 7000 loaded. I live in between the Cascade Mountains and Coast range of Oregon and you must climb a hill to have any fun. It's not a daily driver but fuel is not cheap in Oregon. I am debating over 4.88 nd 5.13's. Does anyone have any input.

 

If you want to keep the tires you are running now, measure the inflated tire circumference, then compare to the circumference of a stock inflated tire that came on a '95 model truck. For heavy trailer towing like 7000 lbs, you need 4.10 gears on a truck with stock tires. The percentage difference between the circumference of the two tires will be the same as the percentage difference in the gear ratios. For example, if the 35 tire circumference is say 25% more than the stock tire, then your gear ratio should be 25% higher to give you the equivalent torque. So 4.10 ratio plus 25% = 5.125. The 5.13's would be your choice in this case.

 

To make the calculation even easier, just measure the inflated tire diameter for both. Since tire cirumference is 2*PI*r, or PI*D, the required gear ratio will be 4.10 * D/d , where D is the diameter of the larger tire and d the diameter of the stock tire.