Tire size vs rpm@highway speed

[greg g]

This chart shows rpm at 65 MPH assuming a 1to1 top gear.

FYI 205 75 15 = 27 in diameter, 225 75 15 = 28 in diameter.

The chart agrees with my dyno run which I did at 6200 Rpm with 225's with the 4.1 rear gears. The tach said 3200 rpm.

http://www.4lo.com/calc/geartable.php

[55 Fargo]

Hey Greg, with my truck and the 3.23 diff ratio, with P205 75 15 tires at 27 inches. At 60 mph this works out to be 2411 rpm, which is not bad at all.

The thing, is this truck needs spring work, shocks all the way around, so at 60 mph she seems choppy. I prefer running her at 50 mph, but the engine is not winding to hard at 50, at 45 mph, yuo can hardly hear the engine.

I did notice something tonight, went to town in the truck earlier, outside temp 82f, wind gusts up to 40mph or so, going against the wind in 4th gear, with the 3.23 you could feel her work. Now it is real flat here, but no doubt in my mind, this truck would labor on big hills with a 3.23 rearend, but I love here on flatland. I do not think I have any reason to try and go the T5 route, but it would be nice to have a smooth shift gate like with a T5 compared to this old stump puller 4 speed trans.

[james curl]

Check for a S-10 with a four speed transmission, I picked up one at the swap meet with clutch disc and bell housing for $75.00. It looks just like a T-5 except it does not have a 5th gear. I was going to use the tail shaft on a Camaro T-5 that I have by replacing the shift gate for the four speed with one from a five speed.