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Discussion Starter · #1 ·
Hey everyone,

Ran into an issue with my 2-9er rim, discovered Friday night as I was race prepping my bike for Sunday. Had to call around to my buddies for some backup wheels, ended up getting a set of plus wheels. Having never ridden plus, I went with the 13 psi recommend by the guy loaning me the wheels. Didn't have much time to get a feel for them before the gun went off (he gave me the wheels in the parking lot before the race). All I can say is SKETCHY. I know this is because my tire pressure was too low, but the traction up the climbs was pretty great, and sending it into the rocks was great.

What PSI are you fellow big guys (210+) riding on the plus wheels? Any recommendations for a starting point? Rims are 40mm internal with a 2.8 tire. I will be doing some testing in the coming days, but would love some input on where to start out. TYIA
 

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Usually a couple to 4 more for the rear than what works for a front. Your terrain and speed through rocky sections will limit you because of rim hits.
1 psi can make a difference so take a low pressure range gauge when you do your testing.
If you don't get rim hits lower until you do. Start where you are or with 15 in the rear.
 

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I am 165lbs and here are my set-ups (all on the same bike)

29x2.3 F/R 21mm wheels - 21 psi F / 27 psi rear - 100mm fork
29x2.6 F/R 35mm wheels 15 psi F / 20 psi rear - 100mm fork
29x3.0 F/R 35mm wheels 11psi F / 14 psi rear - rigid fork


However your pressures may vary. Low end pressure determined by rim strikes. Too many and need to raise the pressure. This is for XC type tires (XR2, Ikon, Ranger etc). The 3.0 were most sensitive to pressures 1 psi high or low was obvious to performance. I use a low pressure gauge to dial in pressures as I don't trust pump gauges
 

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What was sketchy about it?

You say you liked the climbing traction and the rollover, 13 psi is pretty ball park for 3.0s.
Was it the turns? Which kind? Slow and tight or fast and sweeping?
IME, 3.0 wheels benefit from a different riding style than 2.<whatever>. Plus tires like to be LEANED. Like, way more than reg tires. Work it like a motocross bike.

I just got back from a weekend of riding with family and spent some time on my uncles new Rip9 RDO with 29x2.4s. I was quickly reminded that a 2.4 Ardent needs a lot less input to redirect the wheel than my 3.0 XR4, but doesn't 'stick' half as well when leaned over and carving.
I rode his bike for a few miles and when hopping back on my bike with the XR4/XR2 combo, it was squirrelly for a few turns until I rewired my brain back to my bike and all was right with the world again.

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i roll 3.0" chupas on 39mm internal rims....i weigh probably close to 210lbs kitted up on a rigid SS 29er. 11 front/14 rear. i live in santa cruz....lots of loam, sand, dust on crust etc...not super rocky.
 

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Discussion Starter · #6 ·
What was sketchy about it?

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I could feel the tires rolling out and general vagueness through the corners, mostly on the fast sweeping corners. I know it is a pressure related issue, and some adjustment will be required from my normal 29x2.2 riding. I'll be sneaking out for a ride this evening with a pressure gauge in pocket to play around. Probably going to start at 20 psi from the house and drop it until it feels vague again, then mini pump back up. Almost like messing with the fuel screw on the MX bike.

Thanks for the input!
 

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Also going to depend on the tires, how stiff their sidewalls are. I was getting sidewall flex with WTB Trailblazers (granted, they were worn) and then swapped to new Maxxis and haven't felt it sense.
 

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It will also depend on dirt. I ride in mostly loose dirt and low traction cornering. So plus tires never felt vague in corners. Except for 1 day when it rained and dirt was packed like concrete. Then they felt 'tight'. But that is very rare where I ride.
 

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I'm around 210lbs geared up and I've found the ideal pressures for me are something like 15F and 18R, riding a rigid Krampus with 29 x 3.0 tires (Innova Transformer Race). This level works for me in the generally loose, sandy soil that we have where I ride. It's a good balance between cushion over roots and logs but still stable in higher speed sections. If I ride rockier trails I usually have to up those numbers to 17F and 19R.

I also throw on a set of Surly Knards when the weather gets sloppy which I run a few PSI lower because the sidewalls are a bit stiffer and the tread digs in a bit more than the Innovas.
 

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I'm around 210lbs geared up and I've found the ideal pressures for me are something like 15F and 18R, riding a rigid Krampus with 29 x 3.0 tires (Innova Transformer Race). This level works for me in the generally loose, sandy soil that we have where I ride. It's a good balance between cushion over roots and logs but still stable in higher speed sections. If I ride rockier trails I usually have to up those numbers to 17F and 19R.

I also throw on a set of Surly Knards when the weather gets sloppy which I run a few PSI lower because the sidewalls are a bit stiffer and the tread digs in a bit more than the Innovas.
but what kind of rims are you on? that makes a big difference.
 

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Weigh 180 and run 29x3.0 XR2 at 11 front and 13 rear. Mounted to Flow MK3.
Plenty of rocks where i ride.
 

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So shouldn't this thread include the "plus gals" as well? :p
 

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I weight 215 lbs. ready to ride. Running 2.8 Maxxis Rekons on Ibis 735 rims and a 140 fork up front on an all mountain single speed hard tail. Pressures are 20 rear, 18/19 front.

Note that I had a big ledge strike when running 19 psi in the rear and cracked a Derby rim.

Hope this is helpful.
 

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A non-number data point:

When my tires are a bit too low (1+ PSI), they induce some heavy self-steer/want to wallow through turns. When a bit high (1+ PSI) they start to get bouncy.

If you don't have a low-pressure gauge on hand (Meiser, et.al.), you should buy one. You've got a tiny bit more leeway with higher pressure if you are rolling suspension, but not much.
 
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