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Technical Tips

7 Ways To Choose Right Size and Replace Dirt Bike Tires

by YIMIN WANG 11 Oct 2022

Decide the total track circumstance including the beginning line

  • If the circumstance differ from hard-packed to loose loam, you'll likely will want a versatile tire like Dunlop's MX33 or other brand dirt bike tire.
  • For hard terrain, the MX52 is your ideal choice.or other brand dirt bike tire(see column 1 on the below guide chart).
  • For soft terrain, mud or sand, Dunlop's MX12 is the tire of option or other brand dirt bike tire
  • If the conditions differ from hard-packed to loosened loam, you'll likely will want an intermediate terrain tire like Dunlop's MX33F front & MX33 rear or a combination of hard track front & intermediate back (MX52F & MX33) or option other brand motorcycle tire(see column 1 on the below guide chart).
  • If the ground has a mat to it, rutted with soft berms, you probably need a soft terrain tire that will pierce via the loose dirt. Dunlop's MX33 or other brand dirt bike tire(see column 3 on the below guide chart)or is an exceptional selection.
  • If the circumstance are strictly soft deep sand or mud, you may think about a specialty tire like the New MX12 or other brand dirt bike tire
  • Allow the dominant circumstance determine your option after thinking about the start section.

Don't be fear to mix dirt bike tires patterns front and back to feel even more comfortable.

Engine Front Front Option Rear  Rear Option 2.5" Rim 2.5" Rim
125cc 80/100-21 100/90-19
250cc 80/100-21 90/100-21 100/90-19 110/80-19* 110/80-19** 120/80-19***
450cc 80/100-21 90/100-21 120/80-19

 * For Hardpack

**SX Hardpack

***Ultra Hardpack

Pre-Ride Inspection

There are a couple of essential points you must to examine before every ride

  • Examine atmospheric pressure prior to every ride.
  • Make certain the shutoff stem has actually not spun; if it has, decrease tire and re-set.
  • If riding in a rough area or track, ensure to look between the knobs for splits or cuts to the tire carcass.
  • Examine spokes currently.
  • Make sure rim lock is safely tightened up.

Appropriate Inflation Pressure

Appropriate inflation is vital to the life and performance of your tires. Refer to the below chart for right number.

  • Hard Circumstance: Front- 12.5~13.5 psi
  • Hard Circumstance: Back ~14 psi
  • Intermediate Circumstance: Front- 12.5~13.5 psi
  • Intermediate Circumstance: Back~14 psi
  • Soft Circumstance: Front-12.5~13.5 psi
  • Soft Circumstance: Back-11~12 psi
  • Minis:13~14 psi

Changing Your Tires

Follow these steps in removing and installing your new tires.

Dismantling

  1. Lay the rear wheel sprocket side down and the front wheel brake side up.
  2. Get rid of the valve core and loosen the rim locks.
  3. Stand the wheel up and also make use of the flat side of a tire iron to push the rim locks down, breaking them loose from the tire bead.
  4. Lay the wheel down once again and also base on the tire sidewalls with your feet pressing to break the beads loose from the rim. Occasionally, a little soapy water at the tire/rim joint assists loosen the grains.
  5. With the brake side of the wheel up, make use of the spooned end of your tire irons and also place them in between the grain and also rim. We suggest placing them on one side of the valve stem or other. Lever individually, functioning your way around the tire in little increments.
  6. After the very first side is gotten rid of, press the shutoff stem into the rim and pull tube out.
  7. If your wheel has rim locks, take out them prior to beginning removal of the second bead.
  8. Remove the 2nd grain by putting a tire iron under the bead of the brake side of the wheel, after that lever the tire bead over the rim and press it off
  9. Clean the bead location of the rim. Check the rim locks, rubber rim strip or tape covering the spoke nipples areas for damage

 Installation

  1. Install one rim lock, lube one bead of the tire. Lower on the top of the tire and insert one side of the wheel and the rim lock into the bottom part of the tire. Begin levering the first bead on.
  2. Put the 2nd rim lock if your wheel makes use of two. Prior to mounting inner tube inflate to make sure there wan no damage done throughout removal. Examine the nut at stem area for rigidity and seek fractures in the stem. Leave simply enough air in the inner tube for setting up, so inner tube  holds its form.Apply baby powder to the beyond inner tube and inside the tire. This avoids inner tube  from chafing in operation.Install inner tube in the tire thoroughly. Starting at the valve stem openings, uniformly position the inner tube  inside. Be sure the inner tube  is not bunched up in any type of location or aught under the edge locks. Lube the bead with a mild soap and also water option and push a tiny area if it under the rim near the valve stem location. Place one tire iron and begin levering the tire bead on, taking very little bites with each iron. Stick the iron in just far enough past the rim being careful not to capture inner tube .
  3. With each bite, check that the bead of both sides of the tire is as far down in the well of the rim as feasible.
  4. After the final bead area is mounted, make certain the rim locks and shutoff  valve stem move freely.
  5. Pump up the tire and also seat both beads. Ought to the beads not seat correctly, do not over-inflate. Re-lube the bead locations with soapy option and re-inflate till seated effectively.
  6. After the tire is totally blown up, let the air out again after that re-inflate. This permits inner tube to settle inside the tire.
  7. Tighten up the rim locks and adjust the tire pressure

 MX Tire Size Markings

For dirt bike tires, Dunlop changed to the industry tire standards similarly as street tires. However, due to the prior variations in real dimensions, some changes in bike application have actually been needed.

  • When motorcycle tire requirements for width, diameter and load capacity were presented a couple of years ago, they really did not include dirt bike tires. Therefore, dirt bike tires differed in dimensions from one factory to another. Many tire factory marked their dirt bike tires with a size designation that pertaining to tread width.
  • In current tire standards, the designation for size is really the section width, measured at the sidewall, not at the tread. This has constantly put on street bike  tires. A 4.50-18 street bike tire, for instance, would certainly have an area size of 4.50 inch, and also would certainly fit on an 18 inch rim.
  • 3.When statistics tires were presented, the aspect ratio was consisted of in the size marking. A 130/80 -18 street tire had an area width of 130mm, and also a height ratio of 80 percent. This means that the height of the tire is 80 percent of 130mm. As previously, the tire fits on an 18-inch rim.
  • For dirt bike tires, Dunlop changed to the industry tire requirements likewise as street tires. Nevertheless, because of the previous variations in real dimensions, some changes in bike application have been essential. An off-road machine that formerly fitted a 4.50-18 or 130/80 -18 under the non-standards markings, now fits a 110/100 -18 under the new standards. These tire dimensions share the exact same real measurements. A 130/80 -18 is 110 mm wide in area size and, moreover, the area height is likewise 110 mm or 100-percent aspect ratio. For this reason, a 130/80 -18 under the new standard markings is 110/100 -18.
  • With the introduction of 19 inch dirt bike tires, it was needed to decrease the aspect ratio in order to maintain the same outside diameter. To make up for the extra inch in rim size (18 inch to 19 inch) fitted to a 250cc dirt bike as an example, the size would be changed from a 110/100 -18 to a 110/90 -19. The resulting low profile 19 inch tires with much shorter sidewalls have actually offered improved stability performance, while keeping the very same outside tire diameter.
  • Building on the success of the 19 inch back tire, In the mid 1990's, Dunlop became the first tire factory to develop wider, lower series dirt bike tires for rear. The innovation in the 110/80 -19 & 120/80 -19 develops a bigger footprint for enhance grip and bump absorption. In the late 1990's, Dunlop introduced a wider  90/100 -21 front tire to enhance the rear tires. In each case, these width, low-profile tires fit on existing standard-size widths, eliminating the requirement to replace rims.

Wide Size Dirt Bike Tire  Benefits

  • Provides a bigger footprint for boosted grip and improved bump absorption.
  • Dunlop technology developed to harness and transmit power to the track field.
  • Provides a bigger footprint  for boosted traction and enhanced bump absorption. Fits on standard-sized  dirt bike rims

Conversion Chart

Position Rim Size Tire Size To  Tire Size
Front 21" 80/100-21 >>> 90/100-21
Rear 19" 100/100-19 >>> 110/80-19
Rear 18" 100/100-18 >>> 110/90-18
Rear 19" 110/90-19 >>> 120/80-19
Rear 18" 110/100-18 >>> 120/90-18

 

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