Tire size and code: Through extensive testing and customer feedback, performance converter manufacturers have identified the characteristics of many tires. Tire growth, sidewall characteristics, and compounds are taken into account when selecting a torque converter. This testing has also determined which tires work and which don't with automatic transmission combinations. Much of this applies to the newest high-traction street tires now available.
MiscellaneousIn addition, information on your fuel type and if you use nitrous oxide or if the engine is supercharged or turbocharged: The tach type is considered, as is information on motor mount mid-plates, flexplate bolt circle, past performance, past equipment tested, and so on. Expect a barrage of questions before the right converter is selected.
As you can see, one size certainly doesn't fit all when it comes to torque converters. All of the major companies employ skilled technicians with a wealth of information available, but it's paramount that you provide accurate information about your combination. If the selection is done right, the performance of your converter will almost seem transparent. You won't be sorry and the cost of the telephone call is minimal when you consider how poorly your car will run with the wrong torque converter.