The 24(?) Types of Tennis Balls

Part I: Speed and Felt

Tennis balls come in four speeds, three types of felt, and two basic means for producing bounce. If all combinations were possible, this would give us 4 x 3 x 2 = 24 distinct types of tennis ball, and that's before we consider individual brands. If you never thought buying a can of balls was that complicated, you were right. Some of these theoretical types would be completely illogical, others simply aren't manufactured, and for most of us, many of the existing options would be at most an occasional experiment.

Speed

Early in the year 2000, the International Tennis Federation (ITF) amended the rules of tennis to allow three different kinds of standard-altitiude tennis ball to be used in tournament play. Prior to this change, only medium speed balls for standard altitudes and high altitude balls for play at above 4000 feet were sanctioned. Now we also have "fast" balls, intended to quicken slow clay court play, and "slow" balls intended to slow play on the fastest courts, primarily grass. For a detailed explanation of how balls have been made faster or slower, see New Standards for Balls. Here's a brief summary of speed characteristics:

 

  • Slow: larger diameter, same weight. Possibly good for players who need more time to get ready to hit the ball.
  • Medium: by far the most common type of ball. Best for most players in most situations.
  • Fast: hard to find and rarely used. Possibly a good choice for players who like the soft footing of clay, but would like to be able to end points more quickly.
  • High altitude: designed to be easier to control in the thinner air above 4000 feet.

Felt

The felt covering on a ball is designed with a specific court surface in mind:

 

  • Regular duty: designed primarily for clay and most indoor courts. This is finer felt designed not to fluff up excessively. It wears away quickly on the more abrasive hard courts.
  • Extra duty: designed primarily for hard courts. This is denser felt that can take heavy abrasion. On clay, it tends to collect little bits of the court. On clay or slower indoor courts, it gets too fluffy.
  • Grass court felt: basically regular duty felt, but treated to resist staining.

Bounce Production

All tennis balls are made of a rubber shell with a felt covering, but the type of rubber shell used depends on whether the ball is pressurized or not. A pressurized ball loses its bounce gradually as air seeps out, much as would an inflatable basketball. A pressureless ball retains its bounce indefinitely.

 

  • Pressurized tennis balls are by far the most common type. They typically perform better than a pressureless ball when brand new, but lose their bounce fairly quickly. Many players use them for just one match, then throw them away. A study by Wilson indicates that the typical pressurized ball becomes unplayable after a little more than two weeks. Several companies have come out with pressurized balls designed to last longer. Wilson's Double Core ball has an extra inner coating designed to keep air from escaping. Gamma produces a ball filled with nitrogen, which is supposed to leak more slowly.
  • Pressureless balls get their bounce from the structure of their rubber shell, which retains its elasticity without the assistance of air pushing at it from inside. When brand new, they are typically stiffer and less bouncy than a pressurized ball, although Tretorn makes a very lively ball. As they age, pressureless balls get bouncier, because their felt wears down, making them lighter. They are usually discarded when they become so bald that they become too bouncy and lose their normal aerodynamics.

So, of the 24 theoretical ball types, how many can we eliminate?

The following combinations of characteristics are simply illogical:

 

  • Fast with grass court felt, pressurized
  • Fast with grass court felt, pressureless
  • Fast with extra duty felt, pressurized
  • Fast with extra duty felt, pressureless
This eliminates four possibilities.

The following are, to my knowledge, not manufactured:

 

  • Fast with regular felt, pressureless
  • Slow pressureless (of any felt type = three possibilities)
Without these eight possibilities, we have sixteen left in theory, but unless you go to a pro shop, you'll probably find just one: medium speed, extra duty felt, pressurized. If there's another choice, it's probably medium speed, regular duty felt, pressurized: an option worth considering if your balls usually look like they need a haircut after a few games.

A pro shop might have a few more choices.

Pressureless balls are worth a try if you want to save money and don't mind slightly different playing characteristics. It might also be worth the trouble to find the rarer slow and fast balls, just for curiosity.