As some of you know, I recently experienced a flat rear tire due to one giant rusty old nail someone felt like losing along the road our benefit ride was riding through one nice Saturday afternoon. Since I didn't feel like driving around with a punctured carcass (even though the tire guy said it would "probably be okay") I decided to change to some new Metzler tires only to find out that they were 5 years old. The HD mechaninctold me that long shelf life adversely affects the handling and grip characteristics of the tire.. I can imagine that the rubber gets a bit tougher but wanted to make sure what was going on. So I wrote Metzler to find out if this was true, this was their reply, ONE day after I send it to them via their site's contact information. ----- Thank you for your e-mail. Our tests have shown that there are no differences in quality between new tires and five year old tires, after about 200 km homogeneous running, if they were stored correctly before. This doesn´t mean that tires that are older than five years and have always been stored properly during that time, they are no longer useable or are subjected to any qualitative restrictions. By PIRELLI GERMANY GMBH produced brands Metzeler and Pirelli tyres obtain as new if properly stored until the age of five years from the date of production. The "Wirtschaftsverband der deutschen Kautschukindustrie e.V." (Trade Association of the German Rubber Manufacturers) recommends that tires that are older than 10 years are only useable if they always were used under normal conditions before. The storage area for tires shoud be aired moderately, dark, dry and cool. Tyres should not be stored in areas with fuels, solvents, lubricants or chemicals. Tyres not mounted on rims should be stored vertically. Kind regards Pirelli Deutschland GmbH Kundendienst München --- I call this great customer service.. Take care, Kris p.s. I am pretty sure the writer was a native German speaker, some sentences are a bit messed up grammatically, but I think the idea's are clear.