How much can under-inflated tires affect fuel consumption?

• Under-inflated tires increase fuel consumption by about ten per cent.
• Under-inflated tires increase fuel consumption by about five per cent.
• They can increase tire wear and reduce traction.
• Both B and C.
  Explanation:

  "Under-inflated tires increase fuel consumption by about five per cent, as well as increase tire wear and reduce traction."