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Discussion Starter · #1 ·
I am running Karma DTCs on 717s with Stan's. I am used to running pressures around 40. How low of a psi can I run this set-up? I was feeling lazy this morning and I didn't inflate and I was running in the high 20's this morning and it felt pretty good. I have a race on a pretty flat course tomorrow. It may rain.
Questions:
Is higher psi better on flat hardpack like 45 psi?
Is lower psi better in mud? how low can I run? What is the risk of too low? burping? rollover? has this ever happened to anyone?
Does lower pressure increase rolling resistance and lower speed?
 

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The Karmas are one of the worst tires I have ever ridden in mud. No directional control at all. They move in every direction but forward.

Most of your other questions have been discussed at length in the past. Do a search of this board.
 

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-dude- said:
Questions:
Is higher psi better on flat hardpack like 45 psi? YES
Is lower psi better in mud? depends on the tire
how low can I run? see above
What is the risk of too low? pinch flatting (tubes) or losing the bead seal (tubeless)
Has this ever happened to anyone? every day
Does lower pressure increase rolling resistance and lower speed? yes

Shiggy is WRONG about the karma's ability in mud but there is a trick (I almost thru mine out before trying it). It is one a a very few tires that actually works BETTER with increasing the air pressure (sticky compound only). I weigh 165lbs and run 40-50 psi (usually run 25-35 psi for other tires) and it really hooks up well in mud and snow. If you try running it at "normal" pressures it will feel exactly as Shig said because the sidewalls are so thin that you end up riding the rim rails and the knobs get rolled under without any traction at all. It's funny, people either love or hate the karmas and the ones who hate it are either using the wrong pressure (too low) or are heavyweights too heavy for the thin sidewalls to deal with.

G MAN
 

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How can you know if he's "WRONG" where he rides? Do you ride his exact trails also? Some people just like say that word me thinks. Makes'm feel smarter or something. I've raced Karmas off and on since they first came out(one of the very first sets avail from Stan). They are fast, work killer on harpack, and have decent volumn, but I can assure you they SUCK on wet clay here in the SE. Few tires are worse, and I've got over 80 race type tires laying around here. Give me some Mosq Golds anyday over the Karmas for mud duty. Hell, some Jimmy Lights for that matter. I've heard in gravel based mud that they do ok, but not down here. Nope noda.
 

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Duckman said:
How can you know if he's "WRONG" where he rides? Do you ride his exact trails also? Some people just like say that word me thinks. Makes'm feel smarter or something. I've raced Karmas off and on since they first came out(one of the very first sets avail from Stan). They are fast, work killer on harpack, and have decent volumn, but I can assure you they SUCK on wet clay here in the SE. Few tires are worse, and I've got over 80 race type tires laying around here. Give me some Mosq Golds anyday over the Karmas for mud duty. Hell, some Jimmy Lights for that matter. I've heard in gravel based mud that they do ok, but not down here. Nope noda.
Heh heh, no we don't have any mud here in the Pacific NW because it never rains (ROFLMAO). Gravel, sand to clay mud - I've rode it ALL and I'll stick with my post. If you don't think they're any good in mud then you're too fat, have worn the knobs down (happens very easily with the soft "sticky" compound), or are running TOO LOW PRESSURE. Most of my friends use them too AFTER they ditched their mosqs. and pythons so I'm not the only one who thinks so.

G MAN
 

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Gman086 said:
Heh heh, no we don't have any mud here in the Pacific NW because it never rains (ROFLMAO). Gravel, sand to clay mud - I've rode it ALL and I'll stick with my post. If you don't think they're any good in mud then you're too fat, have worn the knobs down (happens very easily with the soft "sticky" compound), or are running TOO LOW PRESSURE. Most of my friends use them too AFTER they ditched their mosqs. and pythons so I'm not the only one who thinks so.

G MAN
Jake, I ride a bit south of you and I stand by my post. The tires were new, I am not fat and the center tread of the Karmas is not soft compound.

In deep, goopy, slimey mud Karmas are little better than a slick. If the only other tires you have used are Mosquitos and Pythons I can see how you might like them in muck. Try a real mud tire (Panaracer TrailRaker, Kenda Knarly, Hutchinson Spider or Schwalbe Black Shark Mud) and you will change your mind. Heck even a Kenda Blue Groove or Nevegal kicks the Karma's butt in the slop.
 

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>> If the only other tires you have used are Mosquitos and Pythons I can see how you might like them in muck. Try a real mud tire (Panaracer TrailRaker, Kenda Knarly, Hutchinson Spider or Schwalbe Black Shark Mud) and you will change your mind. Heck even a Kenda Blue Groove or Nevegal kicks the Karma's butt in the slop.<<

Shiggy, I couldn't AGREE MORE! BUT, let's get back to the original question where the guy is asking about XC racing on flat with the "possibility" of rain! My whole point is that the karma's are "better" than the other low profile XC race tires for mud traction and since they need higher pressure to begin with, also have lower rolling resistance and would be a great choice for him. You wouldn't mount Farmer Johns on your wheels if there was a "possibility of rain" and you were racing, would you?

Ride fast, take chances,

G MAN
 

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Discussion Starter · #8 ·
I went with the Karmas at 30psi

and the rain held off til the last 15 minutes of a 2 and a half hour race. The Karmas were great for the course. They held roots and loose gravel well, but most was hardpack and some field grass and rolling resistance was low. When the rain came it produced mostly wet gravel which the tires held well. I think this tire is better at low pressure in mud rather than high pressure because it is pretty wide and even at high pressures, won't really cut through the mud. If it was full on pouring rain I was ready to swap wheelsets, because Shiggy scared me, for a pair of Panaracer muds at 45-50 psi which are great mud tires but have terribly high resistance on wet grass in particular. I finished our local series 3rd overall in the Expert Vet Class.
 

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Gman086 said:
Shiggy, I couldn't AGREE MORE! BUT, let's get back to the original question where the guy is asking about XC racing on flat with the "possibility" of rain! My whole point is that the karma's are "better" than the other low profile XC race tires for mud traction and since they need higher pressure to begin with, also have lower rolling resistance and would be a great choice for him. You wouldn't mount Farmer Johns on your wheels if there was a "possibility of rain" and you were racing, would you?

Ride fast, take chances,

G MAN
For where I ride/race most of the time I would swap tires and not use the Karmas if there is a good chance of rain. I would not use Farmer Johns (gawd, no!) either. I would use the Blue Groove or Nevegal, Explorer Pro, Little Albert or Jimmy. All are still fast enough for racing and much faster if the conditions turn nasty.
 
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