the aspect ratio does have a little to do with it...but weight has more to do wtih the "harshness" of a ridetsduke said:Just found it. Both 18 and 19 have 55 while 17 has 65.
so some 255/25/18 will be softer then 255/50/18 using your thinking?grometsc said:the aspect ratio does have a little to do with it...but weight has more to do wtih the "harshness" of a ride
18 vs 19....The 18's will not be as harsh due to weight of rim and tire.
For every action there is an equal and opposite reaction....Its basic physics on why it would.
You are trying to compare extreme's....gar187er said:so some 255/25/18 will be softer then 255/50/18 using your thinking?
There are so many variables that go into this...Its not just aspect, it has more to do with weight then aspect ratio. Its that simple. If I took my stock 18" setup, and went to 235/40r18 setup, the only thing I have changed is aspect ratio, it would have a change in ride quality, but If I went from my 18" setup to the factory 19" setup, I would as well notice an increase in harshness of the ride, but I have kept the EXACT same 235/55 series, but I have added a larger rim, that is approximately 6lbs heavier. The 18" setup would ride better and out have better lateral g's then the 19" setup. If you doubt this, look up the effects of unsprung weight on ride quality and performance. The 18" setup will get better mpg's as well....Just saying.Motorman said:size matters! Guys, the only real numbers that significantly affect your ride are the first (width, as in 255) and second, sidewall height (as in 55) which is called the aspect ratio So a 255/65/18 has a softer ride than a 255/55/18 because the sidewall height is the ratio of :
a) 255 x 65% = 165.8 mm of sidewall height (more sidewall= softer)
b) 255 x 55% = 140.3 mm of sidewall height (less sidewall = stiffer)
So a) is a taller sidewall by 25.5 mm. (about 1 inch!) That gives you a softer ride. The 18, 19, or even a 20" is irrelevant to ride quality concerns, as it is just the rubber tires inner diameter and can have almost any mix of the first 2 numbers. Of course "low profile" tires: 19",20", 22" usually do have smaller sidewalls and thus give incredible handling characterisitics, at price of ride. Your call.
Often, same size tire is available, but in different rim sizes, like 18 or 19" . They will ride about the same, if first 2 numbers are same, but the larger rim size just yields a larger, outside diameter tire, with a tiny bit better ride, just by sheer larger overall tire size. (if first 2 numbers are same, when rim changes to larger size, the only way to do it is to increase overall tires size , in order to maintain that same aspect ratio height) Not all vehicles will have clearance to fit a larger rim with same rubber size (first 2 numbers). Check first.
My SRX has 235/55/20" optional tires/rims. The base tires/rims were 235/65/18". Since 55% of 235mm is less than 65% of 235mm, my sidewalls are shorter and ride stiffer, than if I took the base tires/rim package. The overall, freestanding tire height is the same! (wheel well won't take any/much larger without rubbing) Difference is in the shorter sidewall height, to accomadate my larger 20" rim, thus stiffer ride quality.
To be totally correct, yes, as stated above by TSDUKE, rim/tire weight has some effect on ride, usually nowhere as critiical as sidewall size, in my experience however.
Here is a great chart , with pix and plug-ins, for deciding if a tire comparison will fit your overall, wheel-well opening, in different aspect/diameter size tires.
TEST DRIVE the car, with both sizes, if the option is offered. The ride and cost of replacement tire will change, often a lot!
Hope that helps.
PS....yes I am a ride quality loon! LOL