tires size vs. braking
I have P275/55-20" tires that are worn out. I was going to go to P275/45-20" tires, but tire companies tell me it will affect the braking. Is this true or sales pitch?
That is a shorter, lower profile tire, but not effect braking. Recommend sticking with stock. You will lose a little ground clearance
What your probably hearing is that going to a larger rim size by an inch or more will effect braking due to the weight of the new rim and tire.
Tom and DavidH25 know their stuff. I'm a "stick with stock" guy myself. It certainly won't effect your ABS or your ability to stop but then, Ford never has had "Great" brakes. The tire companies may be practicing a little "CYA".
Keep in mind my calculations are purely mathematical and has no correlation to mechanical operation of a vehicle. The vehicle should not suffer any effect on stopping as the width of the tire is the same. I did not calculate the factor that a smaller diameter tire is turning faster at a given speed than one with a larger diameter. However an aspect ration of 45 compared to 55 would indicate the taller tire would be a little more than 1.5 inches taller. Using the formula for circumstance seems to translate to a error in your speedometer of somewhere between three to five miles per hour at highway speed. What effect this would have on shifting points for the tranny I have no idea.
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