#### ksurfier

##### Well-Known Member

- Thread starter
- #76

Are you looking for minimum weight needed and best handling or are you trying to get best range and efficiency?As noted previously, I have the Conti Terrain Contact H/T (LT) in 275/65/20. I'm currently running them @ 47 PSI due to the Pirelli 20" tires calling for that PSI. Their max stated PSI is 80. Is this the correct inflation?

I believe low 60s will get best range and low 50s best ride.

if you want the same load as OEM then you can inflate to ~60 psi.

Range I would suggest is between 55-65 psi (cold).

A very general guide (If running 65 psi, best to check tread wear every 500 miles to make sure it's even, if not lower 5 psi...):

For the LT tires: |

65 psi is 3,000# load per tire |

59 psi is 2,750# load per tire |

55 psi is 2,550# load per tire |

49 psi is 2,300# load per tire |

45 psi is 2,100# load per tire |

Completely empty, 40 psi could support the vehicle (1,800# times 4 = 7,200#) |

Fully loaded, 48 psi is recommended (2,225# times 4 = 8,900#) |

Additional PSI will shrink the contact patch (this will increase stopping distance) |

This is where the efficiency gain comes from and shorter CP means tire rolls more easily... |

The bad side, too much/little and get uneven tire wear. |

Assume total vehicle weight of 7500#

Each tire supports roughly 1875#.

CPs at 50, 65, and 80 psi:

37.5 sq. in. (50 psi)

28.8 sq. in. (65 psi)

23.4 sq. in. (80 psi)

Let's assume CP as squares, so the CP length is shortened from 6.1" at 50 psi to 4.8" at 80 psi.

In theory this could result in a 20-30% increase in fuel efficiency.

Tire | MPK |

48 psi | 1.7 |

55 psi | 1.8 |

60 psi | 1.9 |

65 psi | 2.0 |

70 psi | 2.1 |

80 psi | 2.2 |

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