The diameter is also different. the 45 refers to the sidewall height as a percentage of the width. so, the sidewall of a 235/45R17 is 45% of 235 for its sidewall height vs. 45% of 225 (shorter). This *does* mean different revolutions per mile which will throw off your speedometer. 1. 4282 posts · Joined 2009. #7 · Mar 25, 2014. The 245/45s you remove from the rear can eventually be placed in the front. Therefore it's not really a waste of $400 to upgrade to the 275/40s for the rear. I say go for it. Our Challengers really should have come with a 275/40 rear from the factory IMO. 245/45-R20 tires are 0.96 inches (24.5 mm) smaller in diameter than 245/50-R20 tires and the speedometer difference is 3.3%. Alberta. Jul 7, 2020. #7. On my work truck I run them at 33 - 35 psi instead of the recommended 40 psi for a better ride on gravel roads, and actually get more miles out of a set as well. The gravel doesn't chew the tread up as quickly at the lower pressure. I don't even notice the low pressure light on the dash anymore. 2 days ago · Performance all season tires (17) Performance all-season tires provide year-round grip tuned for enthusiastic driving. They are a step up from regular all-season tires, and they place more 2. the shorter tires will be slightly worse over pot holes and can flat more often especailly in Michigan! 3. the unequal front to rear tire OD may cause issues with ABS lights and speedo. 4. axle height vs. ground will be reduced slightly from 255 /40 setup. 1/4" in front and 1/8" in rear. The price range for BFGoodrich Advantage Control is $113.99 to $318.99 and Michelin Defender is $225.96 to $11,879.99. On average, the Michelin Defender tires tend to be approximately 14% more expensive than the BFGoodrich Advantage Control tires. The price difference can vary depending on the specific tire size and retailer, but the Michelin Wheel Offset Calculator. Use this calculator to determine the effect of changing your wheel width and offset. First enter your current wheel width and offset. Then enter your new wheel width and offset. Next click the calculate button. It will show the clearance between the inside of the wheel and the strut housing. 225/45-R17 tires are 0.11 inches (2.9 mm) smaller in diameter than 225/40-R18 tires and the speedometer difference is 0.4%. The key difference between the 245 and 275 tires is their width, as stated above. The 275 tires are 30 millimeters wider than the 245 tires. Fuel Economy. Wider tires have a lot of weight. Since the 275 tires are wider than the 275 tires, they will be heavier. Heavy tires put a lot of strain on your engine, causing it to consume a lot of fuel. GQj9VIh.