Proper tire pressure
Stellar HDF Member
Joined: May 2014
Posts: 2,486
Likes: 695
From: Huntington Beach, CA
I run what the manufacturer says, which is the same as what my Fat Boy manual says -- 42 in the rear, 36 in the front.
Road Master
Joined: Sep 2013
Posts: 1,091
Likes: 84
From: Southern Maine / Seacoast NH
I think the recommendation to check with your tire manufacturer for proper pressures for your application is the right one. Harley's recommended pressures are for the OEM tires, those may or may not be correct for the tires you're now running.
Generally, running pressures too low will give you more contact patch (and more grip) at the expense of added heat, shorter tire life, poorer fuel mileage and uneven wear. Too much too low and you probably give up stability if the sidewalls don't have enough pressure to support them.
Running pressures too high will generally give smaller contact patch (with lessened traction and longer braking distances), probably less heat generation, and higher fuel mileage.
Always a trade off, but the manufacturer probably can provide a good, safe number as they have an interest in both rider safety and tire longevity when it comes to their reputation.
Generally, running pressures too low will give you more contact patch (and more grip) at the expense of added heat, shorter tire life, poorer fuel mileage and uneven wear. Too much too low and you probably give up stability if the sidewalls don't have enough pressure to support them.
Running pressures too high will generally give smaller contact patch (with lessened traction and longer braking distances), probably less heat generation, and higher fuel mileage.
Always a trade off, but the manufacturer probably can provide a good, safe number as they have an interest in both rider safety and tire longevity when it comes to their reputation.
Seasoned HDF Member
Joined: Jan 2005
Posts: 68,021
Likes: 3,276
From:
I'm going to apologize in advance if I'm in the wrong place on the site, I'm new to the forum. I have gotten some different feedback from tech vs website re: Michelin Commander II tires. I have recently picked up an 07 Dyna Street Bob and I'm kinda confused on psi. Tech says run 42 40, Michelin is at 40 30 I believe. Need some help if someone can chime in. Thanks!
I'm going to apologize in advance if I'm in the wrong place on the site, I'm new to the forum. I have gotten some different feedback from tech vs website re: Michelin Commander II tires. I have recently picked up an 07 Dyna Street Bob and I'm kinda confused on psi. Tech says run 42 40, Michelin is at 40 30 I believe. Need some help if someone can chime in. Thanks!
Seasoned HDF Member
Joined: Aug 2009
Posts: 9,243
Likes: 3,267
From: west Michigan
Looking at the Michelin site, they say "Respect the pressures recommended by the motorcycle manufacturer". The 2007 Harley-Davidson FXDB Dyna Street Bob has original equipment tire size of 100/90-19 for front tires with recommended tire pressure of 30.46 psi, and original equipment tire size of 160/70-17 for rear tires with recommended tire pressure of 40.61 psi. I found all this information on the internet so it has to be right
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Joe Kucinski
Outstanding HDF Member
Joined: Dec 2008
Posts: 2,007
Likes: 353
From: Ohio
You are doing what everyone should do. Front and rear tire pressures 42 and 36 are the optimal inflation values for safe responsive handling. They're
configured that way in order to decrease the bikes tendency to oversteer. And yes it is a bad idea to ride with lowered tire pressure to increase surface contact area. That does NOT improve traction. In fact, it substantially reduces the tires ability to corner properly.
Outstanding HDF Member
Joined: Dec 2008
Posts: 2,007
Likes: 353
From: Ohio
Increasing surface contact does not improve anything. In fact it will dramatically increase the tendency for hydroplaning on wet roads.