The precision of the best balance wheel watches on the wrist is around a few seconds per day. The most accurate balance wheel timepieces made were , which by WWII had achieved accuracies of 0.1 second per day.
In watchmaking the term "wheel" usually means a large gear with teeth on its periphery - great wheel, centre wheel, third wheel, etc. The "balance wheel" has no teeth and therefore is not a wheel in this sense. Some recognise this and refer to it as simply the "balance". For instance Jendritzki (Swiss) and de Carle (English) use the term "balance" rather than "balance wheel". It appears that the term balance wheel is used in America, although the great American watchmaker Henry Fried, described in his obituary in The New York Times as "the dean of American watchmakers" also used the term balance rather than balance wheel.
I purchased tires at firestone last year and had lifetime alignment. This year I took it for a balance of wheels whereby, It cost me $64. I was offered a one time wheel balance at $44 but i opted for the life time wheel balance so that i dont have to pay any bucks in the future.
A balance's vibration rate is traditionally measured in beats (ticks) per hour, or BPH, although beats per second and are also used. The length of a beat is one swing of the balance wheel, between reversals of direction, so there are two beats in a complete cycle. Balances in precision watches are designed with faster beats, because they are less affected by motions of the wrist. Alarm clocks and kitchen timers often have a rate of 4 beats per second (14,400 BPH). Watches made prior to the 1970s usually had a rate of 5 beats per second (18,000 BPH). Current watches have rates of 6 (21,600 BPH), 8 (28,800 BPH) and a few have 10 beats per second (36,000 BPH). During WWII, Elgin produced a very precise stopwatch that ran at 40 beats per second (144,000 BPH), earning it the nickname 'Jitterbug'. Audemars Piguet currently produces a movement that allows for a very high balance vibration of 12 beats/s (43,200 BPH).
A balance wheel's in seconds, the time required for one complete cycle (two beats), is determined by the wheel's in kilogram-meter2 and the stiffness () of its in newton-meters per radian: