Quote:
Originally Posted by skipsmith521
The tire in the photo is newer...replaced it 4 months ago.
Since the numbers on the side wall is approximate, does this mean that one standard golf tire could be 18 and another one 17 inches because of different manufacturer? Even though they are all stamped 18 X 8.5 X 8 ?
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It is worse than that. A difference in size between tires having the same numbers embossed on their sidewalls not only exists between different model tires by the same manufacturer, tires of the same model by the same manufacturer can have different dimensions.
Carlisle Links were tires that were on just about every golf cart that rolled off the EZGO assembly lines for years and one forum member discovered the height of the two of the original Links tires on his cart was over an inch different than the two replacement Links tires on his cart.
Making matters even worse, the MTD (Mounted Tire Diameter) published by some manufacturers isn't accurate. For example, My Carlisle Turf Master tires are stamped 18x8.50-8, Carlisle's website says the MTD is 18.3" and the ones on my cart only measure 17.0" tall.
My cart had Carlisle Links tires on it when I got it and two were worn and weather checked while the two with fairly decent tread had slow leaks. I wanted to stay about stock height, but wanted a bit more aggressive tread pattern that was still acceptable for driving on the grass in city parks. Being only 0.3" taller than stock (or so I thought) wasn't a significant torque loss, so I went with the Turf Masters. A local tire store is a Carlisle dealer and I got them for $55 each installed on my stock rims.
I was fat, dumb and happy until I discovered the motor RPM I was measuring with the tachometer function of a DMM I have didn't match the motor RPM I was calculating with a spreadsheet I was putting together to show speed gain and torque loss vs tire height. Then, for the first time, I measured the height of my tires with a level and yardstick and discovered that they were only 17" tall. I later measured the rolling circumference at max recommended inflation pressure (22PSI) with drive onboard, for four tire revolutions (214.125") and came up with an effective tire height on 17.03953"
In a nutshell, I pay fairly close attention to details and I'm fairly thorough in my research, but I still ended up with tires 1.3" shorter than I thought I was getting. Fortunately, they serve my purposes well in the hills of WV, but I did get hornswoggled.
