Stupid newbie questions

Lowering a vehicle generally reduces aerodynamic drag. Smaller tire diameter should help in city driving as it would be the same as installing lower (higher numerically) ratio gears. The engine has to work less to accellerate. However, the smaller tires would hurt highway mileage. Also note that by changing the tire size the speedometer/odometer calibration will be off. Your mileage calculations will show a reduction in economy unless you take into account a correction factor that accounts for the difference in diameter between your stock tires and the new smaller ones.

Welcome to the forum and thanks for your post. This place has some good administrators that are pretty knowlegable and fairly on top of things. Don't hesitate to ask questions either.

Mike

No such thing as a stupid question. Many people are probably wondering same things and afraid to ask.

According to Mercedes, "Lowering the ride height at speed results in a 3-percent improvement in drag."

It's a common tip to increase tire height for mileage. This works if tire width doesn't increase thus increasing drag further. It will slightly raise vehicle which can result in more aerodynamic drag. Generally it helps highway miles, especially if your vehicle has the power to pull the taller gearing.

I swapped to slightly smaller tires on one of my Chevy Astro vans because I haven't driven for any distance for a few years. It's basically a drive to work vehicle, meaning 7 miles there and 7 miles back. Doing so improved acceleration slighty due to lower overall gearing. The unsprung weight was also reduced slightly which should contribute to around town mileage. You also have to adjust speedo/odo meter readings for the change in tired diameter. I do drive daily on the highway but it's only for short distances. Since I don't exceed 60 mph the smaller tire is not a big hinderance to mileage. It does allow the torque converter to lock up and overdrive to engage a little bit sooner. Like any mileage modification, the only way to be sure for your vehicle and situation is to test, and retest.

We all started somewhere! In the old days that usually meant buying the Allan Wallace books from Carb Research Center. As time went on he started selling George Wiseman's of Eagle Research and others. We're here to help everyone and anyone learn. There are volumes of information on the internet, yet many things that either aren't online or impossible to find. it is our hope to build this site into a one stop shop. Everyone has thier area of expertise that can be used to help the rest of us.

Yours is computers/webdesign etc etc. :prayer: