harley1 said:
hey guys thanks for the fast reply. i understand the whole reprogram. But when you read the sidewall height on the 17s to the 19s.... the 17s have 4.87 inch sidawall and the 19s have 5.08 inch sidewall....... and yeah i love the site you guys suggested i use it all the time when i upgrae rim size. but now do you understand what i am saying, the 19s have a taller sidewall so that should give me more room for 20s. i have never road in a 19 inch terrain yet but i heard they are a lot more harsh even with more sidewall???? thanks again everyone.
Your not understanding how tires are sized I'm afraid...
Aspect ratio effects so much.
17" are 225/65R17
Means section width is 225mm's across, sidewall height (aspect ratio) is 65% of 225, given us a height of 146mm (for sidewall height)
Stock 19" are 235/55R19
Means section width is 235mm's across, sidewall height is 55% of 235, given us a height of 129mm)
So the sidewall is actually smaller than the 17" tires, which is why they ride more harsh than 17's, the smaller the aspect ratio (the smaller the height) which effects how well the tire responds to the road, it stiffens it up. The taller the tire, the more give in the sidewall, it responds better to bumps, and road conditions. This obviously is not considering weights, which heavier tires/wheels will produce harsh ride conditions. Just drive in the 18" vs 19" setup and you will see the difference, and that is a mere 10lbs per wheel, but the same sidewall height. You should not increase much more than the factory setups, or ride quality will worsen (just my rule of thumb)
Btw if you went 20"....255/40R20 would be the ideal size for the LS setup, and require no PCM reprogram