IPA recently introduced the Tire Comparator (Type II), a caliper for comparing tire diameter on dual-mated tires. 

The Tire Comparator (Type II) provides a method of ensuring mated tires are within tolerance.  The sliding tolerance gauge requires no measuring, guessing, or even visual inspection. Just hold it against the tire, and slide across the treads for a quick pass/fail result every time.

Made in the USA from an innovative lightweight yet durable aluminum construction, the portable Tire Comparator (Type II) is a preventative maintenance and service tool for both tire dealers and fleet professionals.

Special tread wear adapter gauges are also available for any rim size making Tire Comparator (Type II) compatible with all dual-mated tires.