Frequently Asked Questions (F.A.Q.)

Typically trailer tires are not balanced from the factory. What we have found is that if someone balances their trailer tires and then pulls the trailer unloaded for some distance that the trailer will bounce without the load and throw a weight. Then you have to re-balance the tires. Also tandem trailers tend to throw weights when backing sharply. So it becomes almost impossible to keep up with balancing your tires. Most people do not feel a difference in balanced trailer tires and non balanced tires, so by far the majority of people do not balance them but it is left up to the preference of the owner of the trailer.

Measuring 4-Bolt Trailer Wheels

Measure a four bolt wheel from the center of a bolt hole, skip one bolt hole and then the center of the next hole. Basically your ruler goes across the center of the wheel.

Measuring 5-Bolt Trailer Wheels

Measure a five bolt wheel from the edge of one bolt hole, skip one bolt hole and then the center of the next hole. In this case the ruler is not across the center of the wheel and you measure from the edge of one to the center of the other.

Measuring 6-Bolt Trailer Wheels

Measure a six bolt wheel from the center of the bolt hole, skip 2 bolt holes and then the center of the next hole. Your ruler goes across the center of the wheel.

Measuring 8-Bolt Trailer Wheels

Measure an eight bolt wheel from the center of a bolt hole, skip 3 bolt holes and then the center of the next hole. Your ruler goes across the center of the wheel.

The tires on a boat trailer might be labeled: ST175/80D13 C

• *ST - These tires are for a trailer (Specialty Tire for trailer use only)
• *175 - The maximum width of the tire is approximately 175 mm at the widest point
• *80 - Indicates the height of the sidewall is 80% of the width (in this case 140 mm)
• *D - This is a 'Bias' tire (D is for diagonal-the belts run diagonally from bead to bead or at about 45 degree angles to the center line of the tire.
  'R' is for 'Radial' - the belts run radially from bead to bead or at 90 degree angles to the center line)
• *13 - This tire fits 13 inch diameter wheels
• *C - The load index (also tires can be labeled with a ply rating, typically a "C" load range is equivalent to a "6 ply" rated tire, "B" is a 4 ply and "D" is a 8 ply)