Instructions

• 1). Using a damp cloth, gently wipe away any dirt or brake residue you find on the mountain bike wheel and tire. While cleaning, pay close attention to the bolt and nut which are holding the wheel to the frame of the mountain bike; you will want this area to be as clean as possible before removing the tire. Once the entire area has been cleaned, allow the wheel to dry for no less than 10 minutes before removing it from the frame.
  
  
• 2). Using your adjustable wrench, carefully remove the wheel and tire from the mountain bike. Because all mountain bikes are different, the size of the nut will vary depending on the model, so be sure to have either an adjustable wrench for this step or a selection of different wrenches to choose from. Once the wheel has been removed, lay it flat on a clean surface; a white bed sheet or large white towel work well for this.
  
  
• 3). Using your standard tape measure, measure the diameter of the tire across the center hub. It is important that your tape measure is stretching directly across the center hub, otherwise a faulty measurement will result. Once the diameter is determined, note the measurement on a piece of paper.
  
  
• 4). Using your standard tape measure, measure the width of the tire's top edge. Because many tires wear unevenly, you may want to measure the width of the tire in several places to ensure an accurate measurement. Once the width is determined, not the measurement on a piece of paper.