235/45-R18 tires are 1.24 inches (31.5 mm) larger in diameter than 225/40-R18 tires and the speedometer difference is 4.7%.
245/45-17 has plenty of sidewall by modern standards. Avoid the potholes you can avoid. Lower the pressures, no more than 33psi all around when tires are cold but at room temperature. So if the car is parked outside, at 30F, you should have them at 31psi all around first thing in the morning. 01-13-2012 10:58 AM #9.
275/45-R20 tires are 1.08 inches (27.5 mm) larger in diameter than 275/40-R20 tires and the speedometer difference is 3.7%.
275/45-R22 tires are 0.35 inches (9 mm) smaller in diameter than 285/45-R22 tires and the speedometer difference is 1.1%.
40" Tire Diameter 40X16R16. 41" Tire Diameter 41X14.5R16. 42" Tire Diameter 42X14R16 45" Tire Diameter 45X14.5R20. 46" Tire Diameter 46X19.5R20. 49" Tire Diameter
In the tire comparison table above, you can see a detailed calculation of the size difference between 245/40 R20 and 245/45 R20 tire. The calculation results are presented in the form of visual infographics, on which tire with size 245/40 R20 is on top, and tire with size 245/45 R20 below. Both in the table and in the graph, the tires are
BIQdiQ. 120 57 264 23 395 249 347 260 174
difference between 40 and 45 tires
