There are lot of buses and trains available from Coimbatore. Train takes 45 mins. Buses take 70 mins.
If you are coming from Bangalore, get a bus from KPN Travels Air conditioned Sleeper service as well as comfortable Volvo services are available or Gokulraj Travels or Sharma Transport. If you prefer train, 2 to 3 daily services are available - an Intercity express in the morning, and couple of services in the night. Make sure you book your tickets in advance as Bangalore-Tirupur seats are always full!.
Coming here from Chennai is much better, compared to coming from Bangalore. Several bus and train services are available and are more frequent. However, advance booking is advised as Tirupur attracts lot of business and general travelers.
Nearest Airport is Coimbatore, well connected with Chennai, Bangalore, Delhi and Mumbai. Couple of International destinations are also served from this airport. Take a cab from airport to reach Tirupur. One-way drop-off into Tirupur would cost about Rs.1200/-. Best bet would be to hire a cab from a pre-paid counter inside the arrival terminal.