Here’s the latest reader question, along with my reply!
Martin asks: I have been thinking about putting a set of smaller tires on my car – which came from the factory with 17 inch wheels – to improve gas mileage by reducing rolling resistance. What do you think about this?
My reply: I think it’s already being done by the factory! If you take a look at cars like the Toyota Prius which emphasize economy, you’ll discover a significant MPG difference between the car with say 17 inch wheels/tires and the same car with a 15 inch wheel/tire package. Rolling resistance and weight are reduced.
But, there’s a catch.
Swapping out wheels/tires that came from the factory may upset the car’s computerized equilibrium. The speedometer and other such (ABS/TCS and Tire Pressure Monitor) may not work correctly without the computer being recalibrated. This is something to look into before you commit to buying the new set of wheels/tires.
Also, be sure that the new set will fit without causing mechanical problems such as unwanted changes to the car’s ride height and be aware that handling/braking characteristics will be affected.
That said, you will save money on gas – and on tires. As a general rule, the 17 inch and larger tires now commonly fitted to new cars are more performance-oriented and so have softer tread compounds that don’t last as long. Also, they have shorter sidewalls, which stiffens up the ride (you feel bumps and potholes more).
Going to a 15-inch package – with tires that have taller sidewalls – should make the car’s ride noticeably softer, too!
Got a question about cars – or anything else? Click on the “ask Eric” link and send ’em in!
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