I have a set of 18x8.5 +40 RPF1s and the fronts im getting 275 Hoosiers. The rears I’m gonna get 235/45/18s. My question is how can I tell if it’s going to be the same diameter as OEM tire specs so I can maintain the speedometer or odometer.
SIZE 235/35-19 FOR EXAMPLE
The dimensions of a 235/35-19 tire are
9.3” wide (section width) & 25.5” tall (outside dia)
The section width is 235mm wide
(There are 25.4mm to an inch) STEP 1) 235mm divided by 25.4” = 9.25” (section width) STEP 2) Multiply 9.25 (section width) by .35 (aspect ratio)
9.25 x .35 = 3.24” (section height)
To find the outside diameter
Multiply 3.24 (section height) x 2 then add rim diameter STEP 3) 3.24” x 2 = 6.48” + 19.0” = 25.48” round out to 25.5” (outside dia)
You can find out the diameter of your tires by checking the specs on Honda Accord Wheel Size and Specs. For example, if you are getting 18x8.5 +40 RPF1s, the diameter would be 26.3 inches. To compare, the OEM tire size for the Honda Accord is 235/45R18, which has a diameter of 29.1 inches. So, you would want to get tires that are close to 29.1 inches in order to maintain the speedometer and odometer readings.