The fundamental elements of the tires are rubbers, fabric, and wire along with some compound chemicals. Main components for the tire are as follows:
TREAD – the main part of the tire that comes in contact with the road. The tread is thick rubber with grooves that run around the tire that are needed to channel away the water.
TREAD LUG – Tread lugs are what come in contact with the road to provide the traction. When in contact it compresses and reshapes, this creates Force Variation.
TREAD VOID – the voids provide space for flexing and deforming. It also provides the channels for water and other elements to be moved away from the “footprint”.
RAIN GROOVE – is the design element of the tread that specifically arranged to channel water away. They run completely around the circumference of the tire.
SIPE – the smaller narrow voids the branch from the tread lugs. They improve the flexibility. It helps reduce shear stress and reduces heat build up.
WEAR BAR – indicators that are raised and located near the bottom of the tread grooves that the tire has reached the wear limit, letting you know it is time to change the tire.
BEAD – the part of the tire that comes in contact with the rim on the wheel. It is reinforced with steel wire and compounded high strength, low flexibility rubber.
SIDEWALL – the area between the tread and the bead. It is reinforced with fabric or steel cords that provides strength and flexibility.
SHOULDER – the part that transitions the tread to the sidewall.
PLY – layers of relatively inextensible cords embedded in the rubber to hold shape and prevent stretching.
Boat Trailer tires differ greatly from Automotive tires. Automotive tires are made to maintain traction through all conditions: pulling, stopping, turning, or swerving. For that reason they must have more flexible sidewalls to keep tread to road contact. The only time trailers need traction is when the trailer brakes are applied. With that in mind, you will want to decide on a tire style. You won't want to get (P) Passenger or (LT) Light Truck tires, but the best trailer control is achieved with (ST) Special Trailer tires.
Radial vs. Bias?
Bias, or cross, has the body ply cords that run diagonally from bead to bead. Usually at angle and with successive plies laying in a crisscross pattern. The crisscross pattern allows the body of the tire the flexibility to give a smooth ride on rough surfaces. Better for increased rolling resistance and less control and traction at higher speeds.
Radial construction utilizes the body ply cords extending from beads across the treads so they are at right angles to the center line of the treads. This ply uses stabilizer belts directly under the tread and are made of cord or steel. The advantage with this ply is longer tread life, better steering, and lower rolling resistance.
When it comes to choosing the replacement tire that you need, all you have to do is look at the tire you are replacing and all the information is there. ST225/75R15 or something similar is the number that you will be looking for.
ST - Special Tire
-this is the type of tire. Passenger (P), Light Truck (LT), or Special Tire (ST).
1 – Nominal width of the tire in millimeters (295)
2 – Ratio of height to width (75)
3 – Radial ( R ) or Bias ( B)
-this tells you what ply you would need
4 – Rim diameter code. (22.5)
After all this information, if you still feel like you have questions or need help, it is always best to talk to the professionals. That is what they are there for. Good luck and happy tire hunting.