Tire Pressure Settings

[Seahorse72]

A few posts mentioned different tire pressures they are running. I just purchased the bike and am waiting for the dealer to deliver it to my house. The manual calls for 34F, 42R. This seems high, especially the rear. The Kawasaki 900 I just sold, 476 pounds, recommended 36F, 42R.  My son’s Z650, which weighs 10 pounds less than the Trident, calls for 32F, 36R. Curious to hear what tire pressures others are running. I’m 5-10 and weigh 185/190 with all gear. Thanks.

[Studio X]

The rear tire pressure recommendation in the manual accounts for a passenger. If you ride solo, 36psi rear is much more reasonable. The first thing I usually do when a bike comes home is to remove the rear pegs. This takes away any temptation to ride two up and makes tire pressure settings much more straightforward.

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[twotigers]

If you were intended to self adjust the tyre pressures then I'm sure triumph would have put some guidance in the owners manual.
I tend to go by the manufacturers recommendation on pressure.. 

[Studio X]

   Good one!

The manuals are written with the lawyers hovering over the tech people. Anything that requires user judgment has been excised to prevent stupid people from suing the manufacturers.

X

[twotigers]

Hmmmm, an American point of view, whereas they do instruct on suspension settings.. 

[Studio X]

My Daytona 675r manual recommends 32f/36r for Daytonas and 32f/42r for Street Triples. Since the bikes weigh essentially the same, the only real difference is perceived (and actual) passenger accommodation.

My Tiger 800 manual recommends 36f/42r. This for a motorcycle that weighs almost 100# more than the Daytona or Trident plus has a payload capacity of 342#. I assume this means (pilot, passenger, luggage).  The Trident has a payload capacity of 452#.

These pressure recommendations are a safe bet. People should pay attention to loads, speeds, temperatures, etc and should feel free to adjust based on handling and wear. Just like at a track day, start with the recommended cold temp pressure and adjust to suit grip, drive & tire wear patterns.

Just to add another log on the debate fire, your suspension settings are also critical to maximizing grip and wear. Since the Trident doesn’t give you much in that avenue, tire pressure (along with rear preload) is your only real place to experiment to maximize handling and ride comfort.

On the fwiw vein - I ran the Michelin Road 5s (same tire as OEM on the Trident) on my Tiger 1050 for several years. They handled and wore really well at 34f/36r. I bumped them up to 40ish when carrying a lot of gear.

Cheerios, Enjoy the ride.

X

[twotigers]

Good point, well made, so Triumph have set pressures to suit what could be the maximum overall payload 

[Seahorse72]

Thanks for the posts. IMO, the recommended settings are a high/low range to cover all possibilities. Since different bikes use the same tire, the settings must be weight critical. 2 up with gear requires the highest setting. Solo riding is a lower pressure setting. I’m comparing my son’s Z650 at 407 pounds to the Trident at 417 pounds. They are of similar design and suspension and tire size. I think the tire sizes are the same. His bike calls for F/R 32/36. I’m expecting delivery sometime this week and will be riding very gently in this cold weather.

[Studio X]

Let’s take this a step further into Math.

A couple of assumptions.
1. Bike weighs 400#
2. Rider weighs 200#
3. Weight distribution is 50/50
4. Tire carcass supports no weight (useful for comparison purposes only)

Total of bike and rider = 600# which means each tire supports 300#.

If rear tire pressure is 42 psi, the contact patch will be 300/42 or 7.15 sq in.

If rear tire pressure is 36 psi the contact patch will be 300/36 or 8.33 sq in - a difference of 15% or so.

Here is where things get interesting. If we assume a fully loaded bike - which could mean a passenger that weighs 150# (total payload 350#) with the passengers weight centered over the rear axle, we end up with a rear tire loading of 450#.

If the rear tire pressure is 42 psi, the contact patch will be 450/42 or 10.7 sq in. We could assume that this is the design limit.

Lets work this in reverse now. Taking the 10.7 sq in result and dividing that into the weight of 300# (solo rider) we get a tire pressure of 28 psi.

An additional way to verify these kind of mathematical musings is to look into hot and cold temps for track day tires. These assume a solo rider at a “brisk” pace. Most are in the 22 to 26 psi hot readings. Yes, i understand that track tires are not Road 5s, but the point stands. Most road tires are over inflated.

The reason the recommendations are so high can be speculated upon - 1, an assumption most riders do not check tire pressures before riding, so an initial high setting gives a margin of error as the tire losses pressure, 2, most riders will not adjust pressures to account for conditions (passenger, cargo load) therefor better to be at the higher end for safety, or 3, a higher pressure tire give a livelier feeling with sharper turn in so the handling for most riders will feel good, 4, higher pressures will generate less rolling resistance/ better gas mileage.There are probably more that my “American” sensibility does not yet account for.

X

[twotigers]