What measuring device to tire manufactures use when putting the size on the side?

I have 26 inch dirt devils, with 5 pounds of air they measure 24.2 inches tall. Shorter than the 25 inch junklops I took off.. So my buddy bout some 28 inch dirt devils (got a good deal) and at 5# they measure 25.5 inches tall. I realize that if I put 20 pounds in it it might reach 28" but on the side wall it says "maximum pressure 7 pounds" ???

Same deal with the Titan and ITP line, We have 27 inch 589 and they measure 25.5 with 7 #

WHAT GIVES???

 

There is alot of things that affect overall tire height. Wheel width, air pressure, which mold they were made in and so on. If you ever talk to someone that races stock cars, they can tell you that no 2 tires will ever be exactly the same! You can mount the tires on narrower wheels and make them taller. Or do like alot of low rider trucks, and mount them on really wide wheels and make them shorter. The plain cold fact is that the tires are just not made to exact specs, and for most things, it's not a problem. Sorry.

 

the only tires that measure true are super swampers [terco tires] i have 27" mud bugs on my atv, and they actully measure 27 3/4 depending on air pressure.

 

I had a set of 25x12.5x12 Super Swamper TSL's and they measured 26" with 3lbs of air. They were so much bigger than the front 25x9.5x12's (which did measure 25&quot that I bought a set of 25x9.5x12 vamps for the rear. Only problem was the vamps only measured 24 1/2" with 15lbs of air. I know alot of guys that race stock cars, and most of them have bought over 20 sets of tires all the same size, only to find maybe 2 that measure the same! I really don't think the tolerances for tires is very close. In my business, it's plus or minus 1/8", to me thats pretty loose. For tires it seems that plus or minus 1" is more likely.