22545-R18 tires are 0.89 inches (22.5 mm) larger in diameter than 225/40-R18 tires and the speedometer difference is 3.4% Justtoday mounted 225 45 18's from stock 215 55 16. Never drove on anything tire that low profile before. The difference in ride is huge, enough so I'm wondering also about what I'm sensing in the feedback from the tires. Still feel I'm feeling the road and not not any imbalance, after after only a few miles of testing. 24545/18 changes the effective gearing significantly. I use a 235/45/18 front and 245/45/18 rear on my OE staggered 400m for the winter and you can feel it's significantly slower at accelerating compared to my summer setup. Thanks for all the replies, feel pretty confident going 245/40/18 et34 square. Inthe tire comparison table above, you can see a detailed calculation of the size difference between 235/55 R17 and 245/45 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 235/55 R17 is on top, and tire with size 245/45 R18 below. Both in the table and in the graph, the tires are TireSize 235/40r18 vs 245/40r18. The main difference between 235/40R18 and 245/40R18 tires is the section width. This means the 245/40R18 tire is 10 millimeters wider than the Inthe tire comparison table above, you can see a detailed calculation of the size difference between 235/50 R18 and 275/40 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 235/50 R18 is on top, and tire with size 275/40 R18 below. Both in the table and in the graph, the tires are Sizedifference between 235/55 R18 and 245/45 R20 tires. In the tire comparison table above, you can see a detailed calculation of the size difference between 235/55 R18 and 245/45 R20 tire. The calculation results are presented in the form of visual infographics, on which tire with size 235/55 R18 is on top, and tire with size 245/45 R20 below. Inthe tire comparison table above, you can see a detailed calculation of the size difference between 225/50 R18 and 235/50 R18 tire. The calculation results are presented in the form of visual infographics, on which tire with size 225/50 R18 is on top, and tire with size 235/50 R18 below. Both in the table and in the graph, the tires are Iam sorry, but I don't see how 1.3% difference in speedometer readout is that big a difference (60 MPH vs 60.8 MPH), it certainly should not adversely affect performace (225 40/18 vs. 235 40/18 ). It will be slightly heavier and wider, but should also give slightly better overall grip. The235/45R18 tire has the following features: the first three digits 235 refer to the width of the tire in millimetres. The second two-digit number 45 refers to the ratio between the height of the sidewall and the width of the tire. R stands for “Radial” and the last two figures 18 indicate the wheel diameter in inches. HSH6H.