Tire Air Pressure

Biquetoast July 18, 2009 3 Comments

(This post is contributed by KTOF member Steell)

I keep seeing posts that the correct pressure to run tires is the one printed on the sidewall.  Now I have publicly stated that that info is garbage, has no basis in fact and may get someone hurt.

Here’s what Dunlop has to say:

Quote:

Follow pressure recommendations shown on the Dunlop Motorcycle Tire Application Guide. Contact Dunlop if year and model are not shown on the current guide and the owner’s manual does not list pressure settings for Dunlop tires.Keep in mind that hard cornering, passengers, heavy loads and sustained high speeds will require higher pressures (up to that indicated on the sidewall).

http://www.dunlopmotorcycle.com/infocenter_tiretips.asp?id=8#tip

And Bridgestone:

Quote:

Always keep the motorcycle manufacturer’s recommended air pressure in both tires. This is an important requirement for tire safety and mileage. Your motorcycle owner’s manual will tell you the recommended cold inflation pressure. On some motorcycles, the recommended front and rear tire pressures will be different. The pressures stamped on the sidewall of the tire are only for maximum loads. On some occasions, these pressures will also be the manufacturers recommended settings as well.

http://www.motorcycle-karttires.com/additionalinformation.aspx

And Pirelli:

Quote:

It is important to always inflate the tire to the correct pressure. Be sure to check cold inflation pressure frequently (i.e. once a week). Although most motorcyclists love to work on their bikes, they seldom remember to check tire pressures. Correct tire pressure, however, is critical for safe handling. Over-inflation or extreme tire pressure will impair your riding comfort and decrease the contact of the tire with the road. Under-inflation or too little air pressure will result in poor handling and the bike will be inclined to “wander.” Improper and insufficient tire pressure will also cause rapid tire wear, an increase in fuel consumption, lower top speed, and provide less control. Remember to check the inflation pressure of your tires weekly. You will find the correct pressure in the operating manual of the motorcycle. The manufacturer’s information is the minimum values only. With luggage or with a second rider the rear tire needs an extra 0.2 bar, and for high speed riding the pressure of the front tire should also be increased by 0.2 bar.

http://www.us.pirelli.com/web/motorcycle/tyres/tyres-technology/tyres-care/Tyre_Pressure.page

And Metzeler:

Quote:

Many tyre damage result from incorrect inflation pressure. Furthermore, the inflation pressure has a big influence on the riding qualities of a motorcycle. The inflation pressure recommended by the motorcycle manufacturer can be found in the bike’s manual and is usually written on a sticker on the rear swingarm or chainguard. Set the suggested inflation pressure on cold tyres before riding. During service the tyre’s warming-up causes a pressure rise that must NOT be reduced. Check inflation pressure once a week. Increase rear tyre pressure by 0,2 bar / 3 psi when riding with a passenger or with very heavy load. Insufficient inflation pressure causes tyre flexing and overheating that may lead to internal damage. Overinflation impairs riding comfort and stability and can result in uneven wear.

http://www.metzelermoto.com/web/products/technology/maintenance/default.page

I think that ought to be enough to make my point, and that is “Anyone telling you to always inflate your tires to the max pressure printed on the sidewall is wrong”, always follow the info in the owners manual.

For Reference: The Kawasaki Motorcycle Service Manual gives the following tire air pressures (measured when cold) for the stock tires:

• ’76 B1- ’79 B4 — Front: 28 psi, Rear with less than 215lbs: 32 psi, Rear with up to 365 lbs: 36 psi
• ’80 G1 — Front: 28 psi, Rear with less than 215lbs: 21 psi, Rear with up to 365 lbs: 28 psi
• ’82 M1 — Front: 25 psi, Rear with less than 215lbs: 25 psi, Rear with up to 397 lbs: 28 psi
• ’83 K1, S2, Y2 — US/CA Front: 25 psi, Rear with less than 215lbs: 25 psi, Rear with up to 397 lbs: 28 psi
• ’83 K1, S2, Y2 — EUR Front: 28 psi, Rear with less than 215lbs: 28 psi, Rear with up to 397 lbs: 32 psi