Stock Tire Size false advertising?

[turblown]

Just out of curiosity I measured the height from the floor to the edge of the wheel-well after I lifted my 2003 TXT. It measured 22.25" in the rear and 22.75" in the front. Working the math backwards from my lift numbers shows that my stock tires are 16.75" in diameter.
Thinking my math must be wrong, I then verified that the stock tire is a 18.5"X8.5"-8" inflated to 22psi and physically measured the diameter to be 16.75".

Am I reading the tire size wrong? I can understand a small amount of difference, but 1.75"? Is this normal for all tires? If I upgrade to 22"x11"-10" will they really only be like 20" in diameter?

[scottyb]

Air pressure and number of ply in a tire really vary the height and width measurements ... Most off road tires run lower pressures... I have 12 psi in my dirt devils

[Kidder]

Pressure plays a big role in tire diameter. I have 25's and at 12 psi there is no scrubbing on the garage door, at 15 psi the roof scrubs on the door, at 20 psi I cant fit in the garage.

[thewskrs]

Tire measurements are listed at max recommended psi according to the numbers on the side wall , with new tread.

[turblown]

Originally Posted by thewskrs

Tire measurements are listed at max recommended psi according to the numbers on the side wall , with new tread.

Seriously? I just went and checked the ratings on my tires... they are rated at 50psi. The most I've seen recommended on this site is around 22psi or so. In reality 22psi seems pretty firm and rides well on the street.

So if my tires were inflated another 30psi and had a little more tread the diameter would go from 16.75" to 18.5 "? That's probably true, but who runs that much pressure in their tires?

Does anyone know the pressure rating on bigger diameter tires, 22" for example? Is it around 50psi also? Sounds like you could take a few inches off the rated tire diameter when figuring out what tire would fit best if you are running a lower pressure.

[Todd Dolfi]

I only run 10# in my 23's and measure just that...rides good though [swamp fox]

[scottyb]

What kind of tires do you have?

[NewtoBuggies]

If your stock tires are worn much you can most likley count on .75 to 1.0 loss in tread (up to 1/2 inch on each side) alone depending on type and brand.

[thewskrs]

Nobody in real life runs the max pressure on the sidewall. But that is how they get the specs. Of course if your tires are made in China there are no standards adhered to!

[pachanga90]

Keep in mind with any tires,carts,cars,trucks,etc..Very few are ever the height they are marked.The Mud-Tires on 4x4 trucks might be a 40" but they usually measure 38"-39".Its just one of those wonderful marketing things.True that pressure and also temperature affect the tires,We used to mount tires for our stock-cars,measure them,and if we needed them a little bigger we'd max the pressure and place them in the sun for a few hours.After that,reset pressure to normal and the tire was larger!As far as the China part,I put a set of Chinese Steer-Tires on a buddys' Semi.Knowing that he would look,i mounted them with all Chinese-Language info facing out.He almost wet himself laughin when he saw it!Ever try to read recommended pressure in Chinese?