I Read a post where the Prius owner wanted to go with bigger snow tires for more ground clearance. He ordered 205 size tires where the tire is 1/2 inch larger in diameter, erroneously thinking he will gain 1/2 inch ground clearance. He will only gain 1/4 inch ground clearance since half of the increase goes to the top of the tire. Tires are heavier, more expensive, speedo will be off, and gas mileage will decrease. Not only that, but thinner tires do better in snow than wider tires.
As I learned a few weeks ago, some folks with the 17" wheel/tire combination go to a 205/50-17" tire. It is almost identical in size to the OEM size 195/65-15 tire and makes the speedometer close . The OEM 17" tire is a 215/45-17" size and is smaller (.4") than the 195/65-15.
A 205/50-17 is 25.1". A 215/45-17 is 24.6", therefore .4 inches smaller than a 195/65-15 which is 25", not 1.2" smaller.
You're right. Thanks for catching that. So, now the question is why does Toyota put a smaller diameter tire on the 17" wheel?
.1" difference is negligible and is the closest toyota can get to 25" size of 195/65. it is only a .4% difference and translates to a very small difference on the ODO for every 100 miles.
