Join Date: May 2007
Location: El Paso, TX, USA
I believe that two factors come in to play in the problem of tank spreading. The fuel softens the plastic, and it's the amount and the weight of the fuel that causes the actual deformation.
A gallon of gas weighs (IIRC) about 6.5 lbs, so 3.3 gallons would weigh about 21.5 lbs. So, most bikes will sit fully fueled when parked with the fuel softening the tank's plastic. Could the weight of the tank is then be partially to blame for pulling it out of shape?
When the problem with tank spreading first came to light, I decided to test the theory above, with admittedly a small population sample: my GT. All it took was a small change in habit patterns.
My bike went into winter storage at the end of last year (as it does each year) with the fuel low light on. It sat for months with a nearly empty tank. I also gas up at the beginning of a ride, not after, so the bike is always parked with the tank nearly empty.
I'm not stopping for gas any more often than I did. Our group rides usually start at a gas station anyway.
Even if my weight theory is all wet, there's still less fuel in the tank when the bike is parked to react with the plastic of the tank.
My 2007 GT has no tank deformation; the tank is still tight in the mounts. Proof? Hardly, but you decide.
2007 Red Ducati GT1000
2003 Lucifer Orange Triumph Bonneville T-100
Photo: The GT at Utah's Bonneville Salt Flats