Irregularities or bumps due to dirt on the rail top surface translate into higher local stress in the contact patch of the tire. It may not be a big effect but the more evenly the stress is distributed, the longer the tire should last. More important is that the larger the tractive force developed through the tire, the more it gets stretched and the sooner it falls off the wheel. So, minimize tractive effort by using larger radius curves, shorter (lighter) consists, and lower speeds. Or just forget it, run however you prefer, and keep spare tires on hand.
MELGAR
