Spotting abnormal tire wear and correcting the cause can significantly extend tire life. Normally, tires will wear evenly across their surface until they reach the wear bars, which are 2/32nds of an inch above the bottom of the tread. When the tires are worn to the wear bars, they should be replaced.
One shot (1.5 ounces) of espresso has about two tablespoons of coffee (about 1/4 ounces). For best flavor, one shot of espresso, or two tablespoons of coffee, should be used to make 6 ounce of coffee drink. Likewise, a 12 ounce coffee drink will taste best with two shots of espresso.
Another factor to keep in mind is the age of the beans themselves -- as they get older, they'll require a finer grind or firmer tamp. Dose. The dose is the amount of coffee grounds that you put into the portafilter for your shot. The proper dose for a double shot should be between 14 - 18 grams, depending on your espresso machine and personal preference. Take a look at your user manual for any tips the manufacturer provides in this regard.