Tire mounting on a homemade tire changer - part 2: mounting
Now that the old tire has been removed from the wheel, we can start looking at putting on a new tire.
The tool for this job is the mounting side of the mount/demount bar:
This works by riding along the inner edge of the wheel lip, forcing the tire into the wheel with the cylinder on the top:
Sometimes you can just shove the first side of a well-lubricated, cooperative tire onto the wheel without using the mount bar. Most of the time, that’s not the case.
Remember that picture of the tireless wheel? Well here it is again for good measure:
When we removed the old tire, one edge of the tire had to be in that narrow, inner part (called the relief valley, depression, etc) in order to stretch the opposite edge of the tire over the wheel lip. The same holds true for installing the tire. One edge needs to be in that narrow section or it will never stretch over the wheel lip.
While holding one edge in the narrow section with your hand, the mount bar slides around the wheel, pushing the tire over the wheel lip. Lots of soapy water helps the process. First one side of the new tire goes over the wheel lip, and then the other:
This is the most difficult part of the whole process and can sometimes result in copious use of four-letter words.
Tada! New tire on wheel - what was once a separate tire and wheel are now a wheel and tire combination!
Hmm… That gap between the wheel and tire doesn’t seem right. While removing the tire involved first debeading it, installing a tire requires beading it. This is simply a matter of adding air pressure until the lips of the tire pop out to meet the lips of the wheel.
Usually, this is just done by reinstalling the valve core into the valve stem and airing the tire up to its normal pressure. If the tire still won’t pop out, you can safely get away with exceeding your normal tire pressure (up to about 50-60psi max on a normal tire, more at your own risk!) to seat the bead, then lowering pressure to normal. If the tire won’t hold pressure and just blows air out the wheel gap, there are a few tricks you can use: removing the valve core can give a bigger “burst” of pressure to push the sidewalls outwards, or tightening a ratchet strap around the circumference of the tire can hold the tire edges closer to the wheel, sealing the wheel gap enough to build pressure.
Once it is beaded, a little spray of soapy water on both sides will confirm there are no leaks from the bead or from the valve stem. If you can see bubbles being formed, you have a leak. You may need to debead the tire and look for something stuck between the wheel and tire. This one is good!
For this particular tire, we’re done. Back into the trunk with this donut.
Because this is a spare tire and won’t see speeds over about 80kph, it doesn’t need to be balanced. Any other tire will need balancing. That will be covered in the next installment.
Here are some good reference videos of tire dismounting and mounting on a different machine, but the same process applies:
Update Aug 14/2012:
Looks good with (finally) a coat of paint.
Cost for tire changing stand and homemade tools:
$20 - junkyard steel and brand new steel
$10 - 2sqft 1/8” thick HDPE plastic
$7 - 3/4 coupler and nut for 3/4 threaded rod
$15 - nuts, bolts, quick-release pins
A bunch of steel from my pile o’ steel