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Tire wear... how it looks, how it occurs.

Why is it that your front tire wears more on the left side than the right? It is because most of the roads in America have a significant crown, and when driving straight ahead, you are traversing a side hill, and must constantly correct to the left to keep the bike rolling straight. This affects only the left side of the front tire. A further characteristic of front tire wear is that front tires wear mainly in the area about 1/3 of the way around the profile of the tire. (A worn front tire has a profile like a snowplow, rather than a round arc.) The center of the tire almost never shows much wear. The sides wear because they take all the forces of directional control, and the tread of the tire at the edges of the contact patch also squirms laterally as the tire rolls straight down the road.

The rear tire, on the other hand, almost always shows the greatest wear right in the middle, since the main forces on the rear tire ar propulsive, and the tire is always slipping a tiny bit as it accelerates the bike. It is rare to have a lot of wear on the sides of the rear tire, unless you ride on twisty roads exclusively. Seen from in back, the tire will have a wide flat spot in the middle, with a sharp radius up to the sides. The minimum allowable wear as shown by the tread wear indicator, "TWI" on the side of your tire, is not a safe limit in our opinion. According to the factory, 2mm is a safe minimum, and 3 mm is the minimum for doing a track day or for intense sport riding.

The actual depth of the tread or tread wear is only part of the equation. The other part is the profile of the tire. If the tire is the same shape it was when new, only with less tread everywhere, then it can be ridden with handling characteristics similar to what it had when new. But if the tire is worn only on the sides in front, and only in the middle in back, then the profiles will not provide good handling, and the tires should be replaced even if the tread wear indicator still shows that it is OK.

Tire pressure has a huge effect on tire wear. Too little, and the tire overheats and wears much faster than normal, as well as wearing in unusual patterns. Too much, and the contact patch is reduced, leading to premature wear in the center of the rear tire. Average tire pressures are in the range of 36psi front and 38-42 psi rear, but there are many circumstances when a different pressure may work better. At the track, we usually run about 30 and 30, front and rear, for example, and in offroad situations, we may run as low as 20 psi. The basic settings in your owner's book should get you in the right range for normal street riding.

Any time you are in doubt about your tires, you should feel free to come in to the shop and let one of us inspect and critique your tires. We'll show you the wear patterns and let you decide how soon you want to replace them, and also discuss what tires might be best for you. This is usually a service function, but I'll be happy to help you with this if you take the time to track me down. - Kari Prager

Battery Chargers?

It is a good idea to use a battery charger occasionally, especially with LT's & RT's with radio-stereo systems. Even if you ride your bike often, you will have longer battery life and avoid the chance of being stranded with a low battery. The right method is to use either a battery charger for a limited time (12 hours or so) or use a "battery tender", which is regulated and cannot overcharge the battery, and can be left on indefinitely. Remember that no matter how often you ride, charging your battery will insure long life. And if you ride your LT infrequently, and for short rides, it is absolutely essential that you get a battery tender and use it to keep your battery in a fully charged state, as there is more drain on the battery from radio & alarm that with other bikes.

ABS lights that do not go out

Low battery voltage can cause ABS warning lights to stay on. The first evidence you may have of low battery voltage is an ABS system that will not self-check properly. The ABS computer will not boot up properly if the battery voltage is a little low. If your ABS lights are reluctant to go out, and you need to try several times, then it is time to charge your battery.

Shifting into first gear from a stop?

If you have difficulty shifting into first gear... This note is for new BMW owners. When you have been waiting at a stop with the clutch pulled in, you have disconnected the gearbox from the engine and the gearset is no longer spinning. When you attempt to shift into gear, you may find it difficult to engage first because the engagement dogs are not lining up with the corresponding slots on the gear. Giving the gearset a little spin, either by returning to neutral, letting out the clutch, and then shifting quickly into first, or by letting the clutch out very gradually while pressing down on the gear lever, till the gearset moves a little, will allow you to select your gear easily. This is a characteristic of BMW's single plate dry clutch design, and not a sign of a defective transmission.

Valve stem caps

Valve stem caps are more important than you think. Frequently we see motorcycles come in for service with missing valve stem caps. This is potentially dangerous if you are a fast rider, as at very high speeds you can lose air from the valve stem valve unless you have the valve stem cap in place. You do NOT want to experience a deflation at triple digit speeds because you neglected to replace a missing valve stem cap. (We have seen it happen, this is no laughing matter...)

Bike washing

Cleaning your bike... Everyone with a new bike wants to take good care of it, and properly so. This caution is about the use of pressure washers and water jets from garden hoses. It is tempting to put that nozzle on 'jet' and blast off any oil or dirt, but you may introduce water into the final drive through the breather, into swingarm bearings or wheel bearings or into electrical connectors. High pressure water, with or without detergent, is not a good agency for cleaning your bike. Use a gentle setting for rinsing, and a soft rag with detergent to remove areas of dirt & oil. Good cleaning agents do not require a jet blast to clean the bike with little effort.

Long life for your clutch

Checking clutch adjustment (cable operated clutches) is a task that every owner can do. This adjustment is easy and often overlooked by owners. Although the clutch is adjusted properly at every service, in heavy traffic and city driving the adjustment may need to be done more frequently. The essence of the adjustment is to have sufficient free play at the lever, so that you know the clutch is fully engaged and not slipping. You should be able to move the lever freely 1/4 to 3/8" or so at the end before feeling any engagement. If you have no freeplay, you are probably slipping your clutch, which will drastically shorten its life. Add freeplay per your owner's book, or come in to the Service Department and ask to have this important adjustment explained to you.