[wilkin250r]

Everybody is tell you not to, but I haven't seen many people post WHY. You're thinking "It's just a little half inch, and the tire is rubber, it will stretch. Heck, it will probably be BETTER, since it will fit tighter."

You're wrong, but let's run some numbers to show you and prove it.

Pi is the ratio of diameter to circumference, and it's 3.1415926535... we'll just call it 3.1416. So the innermost circumference of the bead on a 16-inch tire is:

16 x 3.1416 = 50.2656 inches.

The circumference of the bead surface of a 16.5 inch rim is:

16.5 x 3.1416 = 51.8364

of which the difference is :

51.8364 - 50.2656 = 1.5708 inches.

Now, in order to get a consistent bead diameter and a good seal that won't break loose, the bead area of tire is reinforced with a ring of steel cable. And what you are suggesting, my friend, is that you want that steel cable inside that bead to STRETCH AN INCH AND A HALF!!!!

Steel will stretch, but not that much. You might get as much as 1/4 inch of stretch in a cable 50 inches long (one half of one percent) before it deforms and weakens, but you want to increase that by SIX TIMES, and you're asking if it's safe?

And just to be clear, 35psi is Pounds per Square Inch. A typical 9.5 x 16.5 tire has a diameter about 31 inches, which gives a sidewall surface area of 541 square inches on just one sidewall. Multiply that by 35 pounds on each square inch, you've got 18,935 pounds. THAT'S NINE TONS OF FORCE.


So you're asking a 50-inch cable around the bead area of a 16 inch tire, to stretch not just double, or triple, but six times it's safe limit, and then ask that same cable to hold back nine tons of force? It won't work. That cable is going to break at about a half inch of stretch, which will cause the bead and the rest of the sidwall to split, and that nine tons of force is going to blow that tire apart.