Tire height surprise!!!!!

[Olman]

The only thing is Johnnie---when you are running at speed the tires are going to expand and gain in height. How much--who knows. So don't take the static, cold measurement as an absolute when trying to gauge motor rpms at speed. Just sayin---

[kab69440]

My cart was bought with four Links tires of the same tread pattern. At 15psi, standing the front ones next to the rear ones there is almost an inch of height differential despite the embossed size on the sidewall being identical. I dunno. Maybe the shorter ones are later production?

For whatever it is worth, the used spare I bought a couple of years later to mount on my swing-away carrier is the same height as the front ones.

[scottyb]

Originally Posted by Olman

The only thing is Johnnie---when you are running at speed the tires are going to expand and gain in height. How much--who knows. So don't take the static, cold measurement as an absolute when trying to gauge motor rpms at speed. Just sayin---

I also found this on a quick search which explains some of the common discrepancies we see on the board regarding actual tire height when compared to advertised or designated height.


WARNING: These calculations (and those provided by all online tire dimension calculators) only reflect nominal tire dimensions, which are often subtly or substantially different than the tire's actual physical size and/or the dimensions provided by the tire manufactures.



Actual Tire Section Width is Dependent on Wheel Width

All tire sizes are assigned specific rim widths upon which they are measured (measuring rim), as well as can often be mounted on slightly narrower or wider wheels (rim width range). Therefore, it is important to note that actual tire section width will depend on the wheel width the tire is mounted on. The rule of thumb is that tire section width changes by 0.2" for every 0.5" change in rim width, being reduced if mounted on narrower then measuring wheel and increased when mounted on wider wheels.

[JohnnieB]

Originally Posted by Olman

The only thing is Johnnie---when you are running at speed the tires are going to expand and gain in height. How much--who knows. So don't take the static, cold measurement as an absolute when trying to gauge motor rpms at speed. Just sayin---

Just looking for ball-park estimates.

What happened to me is that I discovered I wasn't even in the ball-park.

[yurtle]

So we have an excuse when we get speeding tickets. Sorry officer/judge, my tires increased in diameter, so my speedometer was reading low.

[JohnnieB]

Originally Posted by yurtle

So we have an excuse when we get speeding tickets. Sorry officer/judge, my tires increased in diameter, so my speedometer was reading low.

Let me know if it works.

[tag50]

So if you buy one replacement tire, it's not going to match and if you buy a new set there're not going to match. WTH, I smell a class action and JohnnieB gets paid for his motor-

[scottyb]

Originally Posted by yurtle

So we have an excuse when we get speeding tickets. Sorry officer/judge, my tires increased in diameter, so my speedometer was reading low.

I have a buddy who tried that ...... the ticket was $150

[radioman]

Originally Posted by JohnnieB

Good catch.

That should have been 3.1415... rather than 3.1416...

For those not familiar with scientific shorthand, the three dots following the last digit on the right, indicates a continuing fraction. The value of Pi rounded to four decimal places is 3.1416, which should not be followed by three dots since it is rounded up rather than truncated.
FWIW: I use 15 decimal places (3.141592653589793) in my spreadsheets.

17' 10-1/8" for 4 revolutions, or 224.125"
Divided by 4 (tire made four revolutions between lines) that is 53.53125"
Divided by Pi (3.1546...) that is 17.039526"

[JohnnieB]

Originally Posted by radioman

17' 10-1/8" for 4 revolutions, or 224.125"
Divided by 4 (tire made four revolutions between lines) that is 53.53125"
Divided by Pi (3.1546...) that is 17.039526"

I sure did mess up those numbers.

Didn't even transpose them, just typed the wrong numbers in the wrong order.

Worst part is that I didn't notice it when I glanced back to see what you were talking about.