Converters & Lookups Calculators

The lookup tools collect reference values that are tedious to find in a manual: torque specs, lug patterns, spark plug gaps, tap and drill sizes, hitch classes and compressor requirements. They are quick references, and the values are common ones, so check your own vehicle's specification for anything that matters.

Which tool answers which question

Air Compressor CFM Calculator: Size a compressor for your air tool based on its typical CFM draw and how continuously you'll run it.
Bolt Torque Lookup: General torque ranges for common bolt sizes and grades -- always confirm the actual spec for critical fasteners.
Hitch Class Checker: Check your trailer's weight against standard hitch classes to find the minimum class you need.
Lug-Nut Torque Lookup: General lug-nut torque ranges by vehicle class.
Lug Pattern (Bolt Pattern) Lookup: Common lug patterns by vehicle type, for a quick check before buying wheels.
Spark Plug Gap Chart: Typical spark plug gap ranges by ignition system type.
Tap and Drill Size Lookup: The correct tap drill size for common US and metric thread sizes.

Why generic values need checking

A torque spec depends on the thread size, pitch, grade, lubrication and the part it holds, so a general table gives a starting figure only. Spark plug gaps depend on the engine and ignition, and boosted or high-compression engines often use smaller gaps than stock. Bolt and lug patterns have to match exactly, and a close pattern is not good enough. Hitch classes describe a typical capacity, but the ratings on your vehicle, hitch and trailer govern.

Common mistakes

Using a general torque for a critical fastener. Use the manual.
Assuming close patterns fit. A near match can loosen under load.
Copying a plug gap from another engine. Use the engine's own spec.
Sizing a compressor on CFM alone. Check the pressure the tool needs.

Guides for this section

Want the background behind these tools? These guides explain the thinking and the numbers in more depth.