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Dry weight refers to how much a vehicle, most commonly a car or motorcycle, weighs without "consumables," which usually means that the vehicle is weighed without any fluids, such as fuel or oil, in it. Wet weight, or curb weight, usually means that the vehicle is weighed with all the fluids needed to drive it. The weight of fuel and engine oil are almost always excluded to obtain the dry weight, and sometimes coolant fluid, brake fluid, hydraulic fluid, and the entire battery are also excluded. The term dry weight is commonly used in motorcycle specifications, and is often mentioned in articles related to motorcycle testing and handling. Dry weight is considered of interest because a lighter motorcycle has better handling and performs better than a heavier one.
There are no set rules or standards for what fluids are included or excluded in dry weight. This means that the stated dry weight of a vehicle can vary greatly depending on who does the weighing. Often, manufacturers will list a dry weight that is lower than that listed by magazines and other media sources. One reason for this is that manufacturers often remove the entire battery when measuring a vehicle "dry," while this is seldom done by others.
The difference between dry and wet weight can be 70 pounds (32 kg) for some motorcycles. Just under half of that difference is usually made up by fuel, while engine oil and coolant fluid make up about a quarter of it. The difference between dry and wet weight varies depending on factors like the size of the vehicle's fuel tank and the kind of cooling system used.
A car usually has a water-cooled engine that is cooled by fluid, commonly water, circulating through tubes in the engine, adding more to its wet weight. Many motorcycles have an air-cooled engine, meaning the heat generated by the engine is released into the air through the cylinder, which is often equipped with metal fins to dissipate more heat. This cooling system reduces the overall weight of the motorcycle.
Another common weight used in reference to vehicles, is gross vehicle weight rating (GVWR). This is the maximum weight a vehicle can carry, including extra equipment, fluids, passengers, as well as cargo. Wet weight, dry weight and GVWR can all be of interest to buyers and riders of motorcycles. However, GVWR is of special interest for touring motorcycles, because these are often equipped and used to carry heavier loads than other motorcycles.
My granddaddy, was so funny. He didn't drive very far when he got old. Mostly, he would drive to town to the store or to a restaurant, or he and grandma would go visit neighbors. One day when I was riding with him he stopped to get gas. He told me to go in and pay. The car was on empty, so I assumed he would fill it up.
He gave me a twenty dollar bill and told me to pay for five dollars worth of gas. I did as I was told, but later I asked him why he only put five dollars worth of gas in the car because he would need more gas the next time
he went anywhere and he would have to stop at the gas station again.
He told me that he never wanted to ride around with a lot of extra gas in the tank because it increased the weight of the car and that made him get less miles to the gallon. It didn't make much sense to me, but I guess granddaddy knew something about dry weight and wet weight and how it affected his gas mileage. I thought he was just to cheap to spend twenty dollars at one time.
I don't know how much of a difference dry weight and wet weight makes when you are driving your car on the streets and highways, but in racing it is a big issue. I was watching a race on TV the other weekend, and the announcers were explaining why some of the cars were not filling their gas tanks on the final pit stop.
It turns out that every bit of extra weight on the race car can slow the car down enough to make the difference between winning and finishing second or third. I had no idea that the weight of gas would make that big of a difference.