If I change from P235/75/R15 tires to P225/60/R15 tires, how much lower will my vehicle be and how off will my speedometer be (how much faster will it read)?Vehicle is an ‘88 Ramcharger, P235/75/R15 is the stock tire size.
you are going shorter and wider but it shouldn't make much of a speedo difference. will lower vehicle about half an inch. you are only going one size shorter which is in factory allowance.
Grimm, These two tire sizes are extremely different. The 225/60-15 is 1.63 shorter and 0.39 narrower than the 235/75-15. And over all diameter is 3.25 smaller. Not a good replacement. Your speedo would be way off! When it would read 65mph you'd only be going 57.69mph. Stick closer to the OE size.
The previous answerer has no idea how to read tire sizes. In a 235/75R-15 The 235 is the section width in mm. The 75 is the sidewall height in % of section width. The R indicates it's a radial tire. So, to compare the two tires. Current tires are 235mm wide, new ones would be 225mm wide. New tires: 10mm narrower, or about 7/16 narrower. Current tires have a sidewall that's 176.25mm tall, or 6.94. New tires have a sidewall that's 141.94mm tall, or 5.58. The sidewall height will be approximately 1.5 shorter, or in other words the tire will be almost 3 shorter overall and about 1/2 narrower. At highway speeds, this can be a BIG difference in the speedometer, and honestly, just stick with the 235/75-15. A 225/60-15 isn't a truck tire size, not for something as large as a Ramcharger.
