Rear axle ratios and impact on towing

rexlion wrote:

But won't the tranny simply choose a higher gear to offset the 10% difference in rear ratio, so that in the end the engine will run at pretty much the same RPM as otherwise?

The short answer is yes. It's all about final drive ratio, which includes gearing in the transmission, rear end, and torque converter. As someone else pointed out, the main difference will be in launching from a stop: since both will be in 1st gear, the rear-end ratio makes the only difference. With an 8-speed transmission, the 3.45 will have you shifting into 2nd gear halfway across the intersection. With the 3.09, it'll be 3/4 of the way across.

-- Rob