Why aren't tires as tall as they claim to be?

now im not an expert on this.....but i think the only way to get a true measurement is with the tire mounted and inflated.

 

I've never measured the rims on my truck so they could very well be 7" wide. But I do have a set of gulf states wheels that are 8" wide. But those are off a 2nd gen.

 

Because they can get away with it.

All the Goodyear mtrs I've seen measure up true or taller.

 

Here's a guess... Maybe if the tire is fully inflated? Cooper st is 65psi max, but I run them at 35psi.

 

Nope.

 

255/85/16 = 255mm x.85 = 216.75 (height)

216.75 = 8.533 in.

8.533 x 2 (top and bottom cross section) = 17.066

17.066 (tire height) + 16" (rim width) = 33.066

OP is saying his tire isn't 33" tall

 

never mind. Here, educate yourself...

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=7

 

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

 

LOL!i was just going to post this

 

THANK YOU THANK YOU VERY MUCH!
That is what I have been trying to say all this time. MEASUREMENTS ARE AN APROXIMATION!

 

Are you measuring with the wheel installed on the truck (weight of the truck compressing tire)? I'm asking because this tire is spec'd for 628 revs/mile, which if you do the math (5280 x 12 / 628 / pi) = 32.1" effective rolling diameter when loaded.

Spec: http://www.greenoaktire.com/shop-fo...6&loaddesc=&pagenumber=1&order=-1&view=single

 

and if you check....a Footlong isnt 12 inches

 

Oh... That's what you were saying?

 

So when tire manufactures stamp the size on the tire they could care less if it actually measures up to the correct size. I wonder why the tires never measure taller than they say.

 

Not at all what anyone could conclude from your first post.

 

Or your second post.

 

You said "some of the height goes with the width"

You never said anything pertaining to tire manufactures numbers being off compared to the tire calculators

 

LOL, no. The difference should never reach the next tire size.

I think your measurement method is questionable. In any case, the other commonly available tire in 255/85R-16 (BFG KM2) is spec'd at 625 revs/mile, which means it's also 32.1" when loaded.

http://www.greenoaktire.com/shop-fo...6&loaddesc=&pagenumber=1&order=-1&view=single

 

Beat me

 

My first post said it all fairly concisely.......unfortunately.

Now all this.