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Discussion Starter #1
If you air down for dirt/gravel, how much do you typically let out? I haven't done this, but plan on giving it a try next time I have significant distances to do off road. A related question, any thoughts on what this does to tire life. And finally, I'm near 300 lbs, am I going to destroy the tires with less air?
 

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Living the Stereotype
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make your own decision.... I tried airing down... only makes me feel like I'm riding on a flat tire,
Same here, that's with Tourances, with different tires, results may vary.

Note that the 'Strom has Aluminum rims, airing down makes them vulnerable to damage from rocks and armadillos.
 

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I aired down after reading threads in the past. I think it was 28 on the rear stock Trailwing. I only weight 160 and ended up flattening out the rear tire and the front wabble increased from uneven wear. That was only for a two day back road rally. Never again. I am on TKC'80s and love them on pavement or gravel fully inflated. I have a set of Heidenau K60's to go on next and for me this looks to be the perfect strom dual sport tire.
link to US distributor http://www.moto-amore.com/heidenau/new/productsnew_b.html
 

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airdown

i would only recomend it if you can afford to replace an expensive wheel . i pesonally can take the risk of bending a wheel
 

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I drop to about 25 when going in rough stuff, I just leave it at street pressure for "regular" gravel (Tourances). You will get beat to death on the rough stuff with full street pressures, IMHO.
 

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What Kinda Bike Is That?
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Stock air pressures. Up on the pegs. And go like heck.
 

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Living the Stereotype
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What Kinda Bike Is That?
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Before taking any of this man's advice, please consider his avatar.
Oh, I thought we were talking about "dirt". Now, water on the other hand.......
 

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If you aren't doing crazy speeds down to around 28PSI works. Even around 32 PSI makes a huge difference.

Note there are tradeoffs here, just lowering the pressure isn't enough - it depends on tires as well.

I typically run a TKC-80 up front and "whatever" on the back when I know I'm doing a long dirt ride.

Last time I ended up with 34F 28R because the front had so much more grip at the front with 32PSI front & rear that the bike felt like it was going to swap ends whenever I braked.

It does help, and provided you are sensible about speed and are on reasonable dirt roads (I'm not always) the rims will be fine even at 28PSI.

The only ding I have was from hitting a washed out concrete culvert at something north of 80pkh with 28PSI in the front, almost unnoticeable - the KTM 990 chasing me needed surgery with a splitting axe to get home and a replacement rim soon after.

The DL rims are *MUCH* tougher than the standard KTM ones :)

Pete
 

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It does help, but most of the time I'm too lazy and I've had no problems.
 

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Evolving Curmudgeon
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The Shinko 705 runs at 33# max front and rear so I just leave 'em at that and can get thru most stuff fine. If I was changing pressures I'd be digging my mini compressor out several times a day. Pain.
 

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Well

The idea of airing down is to increase the contact patch (make the contact area between the tire and the dirt or gravel wider and longer). This comes in handy on soft surfaces like soft dirt or sand in that the tires tend not to dig in so much, a factor on our rather heavy (for dirt) bikes. The unfortunate side effect is that the bike is going to feel more unstable, as the bike can 'move round' more on the tires with the less rigid sidewall, also due to lower pressure. For hard dirt roads, no point in airing down, as you actually want to dig in a little. Gravel depends on personal preference, but I'd rather keep the sidewalls stiff to protect the rims, and communicate what the tires are doing. And I don't do sand on my Vee. Real dirt bikes tires tend to have a little extra band of rubber near the rims, so when running low pressures, the tire, when it folds, protects the rims from damage better. Also, keep in mind, if you're running pretty fast on dirt or gravel (50-60 MPH) and you drop the tire pressures much, you are going to be adding quite a bit of heat to your tires, as they'll be flexing more. I guess the real answer would come from trying a stretch of road/trail each way, and see what works best for you.
 

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Discussion Starter #15
Thanks for all the suggestions. I've pretty much concluded I won't be airing down. I'm only riding gravel roads. Rims are $550-650. I'm near 300lbs. Fear of tire damage. ....
 

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Thanks for all the suggestions. I've pretty much concluded I won't be airing down. I'm only riding gravel roads. Rims are $550-650. I'm near 300lbs. Fear of tire damage. ....
Wise. I run a lot of unincorporated dirt and gravel, I never air down. Can I tell a diff? Yeah, but it's slight enough it's not worth messing with. Ride, stay loose, the bike will handle just fine.
 

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This is a cross/multi- thread post.

There are a few factors I'd consider when airing down:

1. Experience level riding off-pavement

If you have little to no off-road/off-pavement riding experience, then most-likely the only times you've ever experienced losing traction was a moment of PANIC and TERROR which you never wanted to repeat. The DL is a top-heavy beast, more noticeable especially at slower speeds; if you're moving at any speed, there is very little time in between the front-tire starting to slide out and the entire bike going down.

Airing down the front tire, will give the motorcycle a much more PLANTED feeling, and won't "ping" the handle-bars around off minor rocks and bumps. For riders new to riding in low-traction situations, consider airing down the psi to "train", so you can get accustomed to the low traction handling without having to worry as much about the handle-bars being slammed around (sometimes rather violently).

I recently went off-pavement, taking my front Dunlop TR91 down to 20 psi (which was actually lower than I intended, maybe 25psi +/- better), getting back to the pavement with no punctures or bent-rims (the roads were pretty well maintained). I left the rear tire at street pressure (40 psi +/-).

More experienced riders who are used to low-traction conditions probably can do fine running street pressures on most well-maintained forest roads, since they know what to expect to feel in the steering when going over bumps and gravel. The pros of not needing to air-up afterwards, and not worrying about catching sharp rocks thru the tires, will out-weigh the benefits of having softer, easier, handling.


2. Difficulty and duration of road/terrain

Most well used/maintained fire-roads and backroads probably won't have too many big rocks and bumps that pose a serious threat to a tire w/ reduced pressure, especially if you are picking good lines and staying attentive. If you are going on a longer distance off-pavement adventure, with big rocks/slides, harsher bumps, higher-speeds, (usually for more seasoned riders), a low-psi tire will increase the chance of a trip-ending damaged tire or bent rim; (likely worse than a low-side that you can otherwise just pickup, brush off, and go at it again). Depending on your load, airing down (maybe down to around 30psi +/-) will dampen the steering a bit, and still keep the integrity of the tire to resist sharp edges and rim damage. It was said earlier, hitting a square-edged bump at high-speed can damage your rim REGARDLESS of tire pressure (lowering the pressure a bit can even help absorb the deflection in some situations).

If you are only going to be off-pavement for a short time (only a few miles) on easy well-maintained roads, it's probably not worth it to air down, then having to break out the air-pump once you get back to the main road. Just take it slow if you are getting used to the low-traction.

3. "Quality" and characteristics of your particular tires

I think most of the tires available for the DL are radial-belted type (someone correct me if I'm wrong), so at lower pressures they aren't as stiff, making them more susceptible to damage from sharp edges and rocks, especially the sidewalls. I imagine different tire brands/models will have slightly different optimal psi-ranges, anywhere from 20-30 psi; there probably isn't a magic one-psi-fits-all number, but if you were to ask me, I'd say 27 psi is good when going off-pavement under most conditions. Why 27? Just because I like that number a lot! And it seems like a good compromise of both.


Last bit of advice:

Throttle on AS YOU START your turn-in! If you are a new rider trying to get used to the low traction, take it slow, keep the bike upright, easy on the front brake, and use the throttle! Smoothly engaging it whenever things seem to get bad, you'll be amazed how the bike truly wants to keep going when it's under power (and how rider panic and abrupt braking/steering-inputs are what can disrupt this balance).

One of the fun things to do, once your confidence is built up a little bit, is seeing that turn come up and balance the "steer-in/turn-in/lean-over with the throttle rolling-on", giving almost a 'snowboard carving' like feeling as you plow through the corners. Grabbing "too much" throttle can be more exciting, but rarely will it slide the whole rear-tire out from under you unless you are in first gear over some really loose material. It can also result in a high-side if you suddenly regain traction, but if you are standing on the pegs with your weight forward, it's less likely.

Have fun out there!
 
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