It depends on the car. Some read speed from a front wheel and others from the transmission. Generally speaking, however, others are correct in stating you will be going slower than the speedometer indicates. It also will change the overall gearing if the car is front drive. However, a pickup or rear-drive car sometimes works better with smaller front wheels.
If the car has front wheel drive, the smaller diameter tires on the front will make your speedometer read faster than you are actually going. Probably not a lot. Maybe 3-5 mph difference. You can get on the freeway and check the mile markers.
Yes, it might well mess with the speedo and/or odometer.
Over a fixed distance, the 15" wheels will rotate more times than the 16" wheels. Assuming that the speedo is taken off the front wheel drive, then the car will actually be going slower than the indicated speed, and will cover fewer miles than indicated on the odometer.
my parents have a car and couldnt afford to replace the 16 inch front tires when they wore out. so they took 2 15 inch tires/wheels off a car they no longer drive and replaced the worn out tires with them. Theyre a bit skinnier, too. So now this car has wider 16 inch tires on the back with skinnier 15 inch tires on the front. i know some high performance cars come from the factory like this. but is the smaller tires on the front causing the speedometer to be wrong, since the car didnt come from the factory like this?
