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This is also why I got a PX

April 27, 2007
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When I picked the PX up from its 4000-mile service, there was a note on the worksheet: the rear tire was getting worn. In the ET’s case, 4000 miles meant “worn out.”

Any scooter’s rear tire is going to wear out more quickly because that’s where most of the weight is. Same deal with a car; most modern front-wheel drive vehicles will use up their front tires much more quickly. That’s why the owner’s manual will recommend rotating your tires.

You can do that on a PX, too.

Remember, the design brief of the original Vespa called for wheels and tires of the same size on both ends. This made a spare tire feasible. Ditto for tire rotation. Rotation in this case means changing wheel positions, not spinning the tire on its axle. Just so you know.

Removing the front wheel nuts

You’ll recall when the PX got the flat tire, the spare went on the rear wheel, and the punctured tire became the spare (once it was repaired, of course).

My plan is to move the spare to the front, move the front tire to the rear, and have the worn rear tire become the spare. Why? The spare, having the lowest miles of use, will have the least-worn tread. The least-worn tread will do the best job of removing water when you ride on wet pavement, and will clear a path for the rear tire. Maximum wet traction will thus be achieved.

The front tire goes to the rear because it will have considerably more tread than the rear, even if it has gone more miles. Again, because most of the weight is on the rear, your front tire will probably rot off the rim before the tread wears out. Personally, I’d rather put that tread to good use, so that’s why the front tire will now bring up the rear.

The worn rear tire will now become the spare. There’s still some tread left, so it could serve on either end for a while… say on a rally weekend involving a road trip to Portland or Vancouver, B.C., where putting on 700 miles is a real possibility.

The front wheel will be the easiest. You don’t even need a jack, or need to lay the bike on its (engine) side; the front wheel’s in the air. Remember, the bolts on the rider’s left side are the ones that hold the wheels to the hubs. In front, these align with the spokes. Squeezing the front brake lever while loosening the bolts will give you the most leverage.

A 13 mm socket on a ratchet will get ’em off quickly and easily. Remember, there are lock washers, so save them if you’re going to re-use them, or put on new ones when you put the wheel back on.

As always, I took advantage of having things apart to clean them. A clean vehicle is just more pleasant to work on. It’s also easier to set the tire pressures with the wheels off the bike. The manual sez front tire pressure should be 18.9 psi; I round it off to 19. The tire gauge isn’t that accurate. The spare had about 30 lbs., so it just needed some air let out.

Reinstalling is the reverse of removal. Tighten the wheel nuts in a star pattern, that is, tighten one, then tighten the one most nearly opposite, and so on. I’m told the torque spec is 14-19 ft./lbs., but my torque wrench starts at 20, so I do it by feel. Many years of wrenching on race cars has shown what 19 ft./lbs. feels like. If you use a 3/8 drive ratchet, tight without leaning on it should be fine.

Here’s the wheel chock

We now turn our attention to the rear wheel. You saw from the link above how I chocked the front wheel and jacked up the rear of the bike last time. Notice the better picture of the chock. You can make one out of three pieces of 2×4; use wood screws instead of nails to hold it together, and you can also use it when trailering your bike.

As before, jack the back up so the wheel is as far off the ground as possible with at least one foot of the center stand still touching the ground. Loosen the nuts, pop and drop the wheel. When putting the new wheel on, try to put it up into the body as upright as you can… it’ll go in more easily. Again, you might find it easier to set the tire pressure before reinstalling the wheel. If you ride solo, that’ll be 26.1 (ehh, 26) lbs., two-up is 36 or so.

Same deal as with the fronts; tighten the bolts in a star pattern, and remember those lock washers! Pressing the brake pedal with your hand will give you more leverage (not to mention showing how well-adjusted the brakes are). Before reinstalling the rear wheel, I took advantage of already being on the dirty floor and having the wheel off to… clean it!

Cleaning the rear brake drum

All that’s left is to reinstall the spare on the body bracket, and you’re done. Be sure the valve is on the bottom, so you can check/add air without having to take the cowl off and remove the spare. Your life might be easier if you pump the spare up to about 40 lbs… you can just deflate it to whatever pressure is called for if you need to use it. That way, you don’t need to worry about having a pump or finding air.

As the Deteriorata says, rotate your tires. Do that, and you can go placidly amid the noise and waste. Favicon

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