Triumphrat

lindsayt · 07-14-2009, 01:05 PM

Okay, so I know this is dumb, but as a motorcycle commuter I check my tire pressure every Monday, and I did all my suspension work last Monday. I don't know if I failed to check my pressure last Monday when I did the suspension work or what, but yesterday when I checked it, it was surprisingly low - about 6 psi low in the rear and almost 8 psi low in the front. I brought it back up to my normal pressures (38 rear, 34 front) and now my suspension feels a bit too harsh. Apparently in my haste I tuned it up with the tire pressure too low, but it points out that lower pressures make the ride more comfortable.

So to try and soften the ride back up a little I reduced the preload front and back but that just makes it feel less precise but no more comfortable; I intend to put the preload back where I had it this evening, as it really handles well, but I would like to make it a little softer.

I guess my real question is, can I run the tires a little on the soft side to soften the ride a little? My pressures were *too* low, but they did make for a very comfortable ride. How much can you reduce the tire pressure before it becomes a handling issue? For example, whereas I normally run 34 / 38, I know it's good at 32 / 36, but how about 30 / 34? What about 28 / 32? I'm kind of thinking I might try 30 / 34 and see how that goes; opinions?

Gob-ny-geay · 07-14-2009, 01:49 PM

This is a great question. Most manuals assume "average" weight... which is what? I'd guess maybe 150? Others please chime in.

If you are well above that... a little more pressure helps. If you ride two-up, add a few more psi, but never exceed the stamped "maximum" on the sidewall, usually around 42 psi or so.

Under pressure? I would think tire heating and cupping / cebter flatspotting would result.

Metzeler and Dunlop both have good info on their sites, and I'll close with suggesting never to go BELOW the manufacturers recommendations.

Cars do this under-pressure gimic when new to offer a super soft ride, but then again, cars have FOUR tires, and normally don't lean into twisties on their sidewalls either!

Others?

CHRIS211083 · 07-14-2009, 02:15 PM

OK, adjusting preload wont make the ride softer. thats the damping. adjusting the preload only makes the sping become loaded earlier (to maintain ride height with a pillion) and wont give you a softer ride. as for the tyre preasure, running it low will cause the tyres to wear quicker and your handleing will become bad!!! if you have baught sports shocks then that will make it less comfortable hence why adjustables are good if you dont mind paying for it. i would put the correct preasure back in and see if you can get use to it? good luck.

lindsayt · 07-14-2009, 02:39 PM

Thanks for the opinions, that makes sense. Don't get me wrong, it's not a big deal - it's just that I noticed the ride being noticeably more bumpy on our crummy roads once I brought the pressure back to where it should be. I'll keep the pressure where it should be and mess a little with the rear damping settings; in the front I'm using the intiminators so don't think I have too much control over damping but don't think it'll be a big deal - just trying to fine-tune.

ohiorider · 07-14-2009, 03:28 PM

Most every bike I've owned in the past, aside from the Triumph, specifies two (or 3) different tire pressure levels:
a. Solo rider
b. Two up riding
c. two up with luggage

The W650 spec'd it somewhat differently
a. under 225 pounds weight
b. over 225 pounds weight

The Kaw, which ran tires close to the size of the T100 called for:
28psi front (100/90-19)
32 rear (130/90-18) under 225 pounds
-----
28psi front
35psi rear over 225 pounds

The above may not be on the money, but very close, as I recall.

Also, I have no idea if the rims on the T100 differ in how the tire bead grips it vs rims on another bike .... maybe of no consequence.

I'm running a few # lower riding solo on the front and rear of my T100 .... say, 32/35.

I'd have to believe Triumph may have taken the path of least resistance, and simply said "37/34" all the time, under all conditions.

Bob

koifarm · 07-14-2009, 05:56 PM

IMHO I would not consider purposely run with lower than recommended tire pressures. Tire pressures are put on the tires for a reason by the manufacturers. To change, lower or raise pressure for any reason seems to me to be counterproductive to correct handling , tire wear and cornering capacity.
If you need adjustment for any reason, use the preload settings on your rears, different shims and springs in your front forks.
Just sayin'

roxythruxton · 07-14-2009, 06:12 PM

I usually keep mine about 2 lbs over . Works for me .

mikeinva · 07-14-2009, 06:47 PM

the tire pressure they list is what it takes for max load you can run alittle less and it wont hurt a thing.

road dog · 07-14-2009, 08:01 PM

Quote:

Originally Posted by roxythruxton

I usually keep mine about 2 lbs over . Works for me .

I generally keep mine a couple lbs. under... for a smooooother ride.

ohiorider · 07-14-2009, 08:01 PM

Quote:

Originally Posted by koifarm

IMHO I would not consider purposely run with lower than recommended tire pressures. Tire pressures are put on the tires for a reason by the manufacturers. To change, lower or raise pressure for any reason seems to me to be counterproductive to correct handling , tire wear and cornering capacity.
If you need adjustment for any reason, use the preload settings on your rears, different shims and springs in your front forks.
Just sayin'

I think there's two different sets of numbers being discussed here. You're referencing the max pressures stamped onto the tire .... I think Lindsayt is questioning the tire pressures Triumph publishes in their Owner's Manual, regardless of the brand of tire on his bike. And as I mentioned in a previous post, most bike manufacturers provide pressures for solo riding, double up riding, and double up with luggage. As the load on the bike increases, they specify higher pressures. Triumph, for some reason, picked one set of pressures for the front and rear tires, and does (let's be British ....'do') not provide different pressures for the load the bike is carrying, which isn't in keeping with 90% of the world's bike manufacturers.

Bob