Photo shows a tear in the sidewall, with a wire to make it obvious.
Photo shows a tear in the sidewall, with a wire to make it obvious.
Booting a ripped tire.

A ripped tire is bad news. It doesn't perform well, can't be pumped up fully, and the tube bulges out through the rip, just waiting to pop. By applying a tire boot, you can ride on the tire. This will get you down the trail, and if the rip isn't too big, it may even let you ride the tire until the tread wears off.

But I wouldn't recommend jumping off ledges with a booted tire. Repair the tire and salvage your ride. But first chance you get, buy a new one. Put the repaired tire on your kid's bike, or give it to your neighbor who only rides pavement.

Cleaning things up.
Cleaning things up.
First, get the area clean. Wash the inner-tube talc and the trail dust off the area of the rip, both inside and out.
Bigger is better. Thicker is better.
Bigger is better. Thicker is better.
Pick out a large rubber patch. For a tiny rip, a 1-inch by 2-inch will do. For a major rip, you want a big mutha -- at least 2x2. The best source for these big patches is a car tire patch kit, which you can pick up at the auto parts store.
Prepping the rubber on the inside of the tire.
Prepping the rubber on the inside of the tire.
Rub the inside clean. I try to avoid sandpaper on the inside of the tire. But if you need to remove some buildup, sand VERY sparingly on the inside. The cords are covered by a very thin layer of rubber. If you sand this thin layer of rubber off and expose the cords (the "strings" that give the tire strength), the patch won't stick well.

Also lightly sand the outside, being careful not to expose the cords. If there are raised letters in the area, smooth them off so the outside patch can cover them.

Use patch cement.
Use patch cement.
Apply rubber cement to the outside, and rub it into the exposed cords in the hole.
Applying adhesive to the inside.
Applying adhesive to the inside.
Spread rubber cement on the inside, about half an inch wider than your boot. Remember that thicker is NOT better. A thin coating will actually make a stronger bond.

Wait until the cement is dry -- both inside, outside, and in the exposed cords.

Exposing the sticky side of the patch.
Exposing the sticky side of the patch.
When the cement is non-sticky to touch, peel the backing off the big inside patch.
Pressing the tire boot into position.
Pressing the tire boot into position.
Press the patch down firmly, centered over the rip. Massage the patch onto the tire, also "squishing" the exposed cords on the outside down, so the outside seems sealed.
The inside was the important part. But the outside patch adds strength.
The inside was the important part. But the outside patch adds strength.
Pick out a small patch for the outside of the tire. This patch should cover the exposed threads inside the hole and reinforce the inside repair. But an outside patch can't can't cover the tread, and it should NOT go into the area where the tire must contact the rim.

Reapply a very thin layer of rubber cement to the outside, then wait until it's dry to touch.

Finished with the outside patch.
Finished with the outside patch.
When the glue is dry, press the outside patch into place. Your tire is now ready to go back on the bike.
Matt actually rode this wheel down the Portal Trail.
Matt actually rode this wheel down the Portal Trail after ripping a huge gash while jumping the Golden Crack.
Hint 1:  Duct tape works for temporary repair of small sidewall cuts.

Hint 2:  Wrap a strip of inner tube around-and-around the partially-inflated new tube at the place where the sidewall is ripped, before putting the tube back in the tire casing.

Hint 3:  For large tears, or for long rim cuts (such as this 4-incher on Matt's rear wheel), put cable ties around both rim and wheel. This keeps the expanding tube from pushing the repair open.

Hint 4:  A dollar bill, folded in half, is strong enough to keep a tube from bulging through a cut in the tire.