Tire math

There it is, plain as day, worked out on a napkin at Panera Bread Co. the other day – the math leading up to today’s purchase of a set of Michelin Pilot Road 3 tires for my 2003 BMW K1200GT.

The tires on the bike now were installed in August, 2010 by the BMW dealer in Champaign, Ill. and have 8,520 miles on them. They are Michelin Pilot Road 2 tires which are a dual-compound – harder in the center and softer on the sides for long wear and good traction in the turns.

They replaced another set of Pilot Road 2s that still had a few miles left in them after 9,607 miles. So, given those numbers, I’ve got at least another 1,000 miles of riding left on my present set and probably a lot more.

The most miles I’ve ever gotten out of a set of tires on this bike was 11,650 on a pair of Metzelers.

The tread depth is still good – about double what it takes to pass the “penny test” where you insert a penny into the tread with Lincoln’s head first. If there is enough tread depth to reach the top of the Great Emancipator’s head, you’re good to go. If not, time for new tires.

So I figure I have more than enough tread left for the European Riders Rally next month in Burkesville, Ky. (800 miles round trip) and almost certainly for the BMW RA Rally in North Carolina in June (1,108 miles round trip). But there is no way they will last to the BMW MOA Rally in Salem, Ore., with a side trip to Portland and down to Big Sur (<> 5,900 miles) in July.

If I wanted to get the most possible miles out of my current tires, I’d plan to replace them after the RA rally. But if I want to get it done well below dealer cost, I need to order them from Motorcycle Superstore and mount them myself, which means with the assistance of BMW friend Charlie and his No-Mar tire changing equipment.

(The Champaign dealer charged me $508.62 – $144 of it labor – for my current tires. The Pilot Road 3s I ordered today came to $347.98 with free shipping. That’s a saving of more than $160 over what I figure I’d have to pay at a dealer, especially since the Pilot Road 3 is a more expensive, improved version of the Pilot Road 2.)

The tricky part here is that Charlie and his wife Deb won’t be around between the RA and MOA rallies because they’ll be on the road from North Carolina to Oregon. So if I want Charlie’s help and equipment, I’ll have to re-tire before the RA rally.

That’s why I pulled the trigger on new tires today.

It’s all right there on the napkin.