Q: I put a new set of Michelin Primacy Tour A/S 235/55 tires on my 2017 GMC Acadia 7,000 miles ago. They are riding really hard. They're supposed to be quiet and smooth riding. Can these tires get hard?
A: No, new tires don't get hard. Be sure they are inflated to the pressures found on the car's door. Some tire techs mistakenly inflate the tires to the maximum pressure figure molded into the tire's sidewall.
Cool it
Q: My 2008 BMW 328 with a six-cylinder engine and 82,000 miles runs beautifully. But once the temperature gauge reaches 180 degrees Fahrenheit, the electric cooling fan comes on full and stays on, even in cold weather. When I park, it takes 30 seconds for the fan to wind down from its stratospheric RPM. Is this normal?
A: Yes, it is normal. The engine is happiest when running at the designed running temperature. In your BMW's case, that is about 200 degrees — even in cold weather.
Gas guide
Q: We have a 2013 Ford C-Max and a 2020 Ford Fusion. We usually burn 87-octane gas containing 10% ethanol. Lately I'm seeing 88-octane unleaded with 15% ethanol. I know we shouldn't use E-85, but I'm wondering if we could use the 88-octane with more ethanol.
A: As of the 2013 model year, Ford vehicles can use E15 gasoline, while prior model years are limited to E10. To see fuel requirements specific to your vehicle, check your owner's manual. By the way, E15 has 85% gasoline, the opposite of E85, which has 15% gasoline.
Rough idle
Q: I have a 2012 Hyundai Elantra with 87,000 miles, and the idle is sometimes a bit shaky. The Hyundai dealer told me to use fuel system cleaner or super unleaded, but it hasn't helped.
A: After a decade of driving, the idle air control valve might be getting dirty. When that happens, idle is often uneven, especially on a cold engine. A thorough throttle body cleaning might be all you need.
