More Information on Andy’s Track Testing - Expanding on the Topic Explored in Vol. 35 No. 7

I received several emails from people with comments and good questions about my column in issue 35-7 where I tested several combinations in a slalom and lane change course. As well, I noticed a couple of errors that I should have picked up when I proof read it. I spent so much time trying to get this down from six pages that I missed a couple of critical points.

Points of Clarification

1) The front tires on the 2003 1500HD truck were changed from 245/75R x 16” to 225/75R x 16”. This is a change we make frequently on two-wheel-drive trucks. We need the 245 tires on the back for load carrying capability, but the front axle runs much lighter. The 225 tires fit the seven-inch rim better, so they have tighter steering response, less tendency to hydroplane, and a little less rolling resistance. The combined effect is quite noticeable. If you wish to do this to your own truck sometime, send me an email first and I will make sure it is ok for your combination. The sizes are close enough that it does not affect the anti-lock brakes. On many vehicles you would never make a change like this because it would affect the balance of the vehicle at the limits but that is not an issue with a long wheelbase pick up truck.

2) The Suburban I used was a 2004 1500 4X4. I had the factory rear-air shocks, which are quite good but the front suspension has been upgraded with heavy-duty gas-charged front shocks.

3) The stock tires on the 300C were 225/60 x 18” not 225/70 x 18”.

Addressing Questions
I have a 2002 half-ton with a 4,500-pound trailer. Would better shocks help significantly with the lighter trailer?

Even while not towing, some new high quality gas shocks will make a substantial improvement. Because shocks wear out gradually, you may not notice how bad they are until you put the new ones on. I just installed a set of the new Koni FSD shocks, and was very impressed with their combination of ride and control.

In the test results you show very interesting details. However, what are the differences between the tow vehicles by themselves versus the combined set?

We don’t actually test the tow vehicles by themselves as others, with a lot more resources and better test conditions, already do. We do use the same 100-foot Slalom that Road and Track does, so if you look up their road test summary you will get an Idea of how various vehicles do on their own. At one time there was a test on a full-sized SUV that did not do much better than some of our combinations did. One difference is the drag strip has a slight crown to it and a few bumps where as they use a perfect skid pad. Their conditions are certainly going to be more precise, but the crown and the bumps are more like
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(Read the full article in the magazine.)