Fitment & spec guides

Short explainers for the numbers on our spec pages.

• Bolt pattern explained: what 6x139.7 means
  How lug count, pitch circle diameter and center bore decide whether a wheel fits.
• Towing capacity explained: trailer, tongue weight, GCWR
  Why one truck has a dozen towing ratings, and which limit applies to you.
• Engine oil viscosity explained: what 0W-20 and 5W-30 mean
  Reading an SAE oil grade, and why the capacity figure includes the filter.
• How to read a tire size: P245/75R17 and LT285/70R17C
  Width, aspect ratio, construction, rim size and the P/LT prefix.
• Battery group sizes explained: 24F, 48 (H6), 94R (H7)
  What BCI group numbers mean, the H/L names, and how to check yours.
• Wiper blade sizes explained: driver, passenger and rear
  Why the two front blades differ, and what to check besides length.