tmoritz

I just changed over to my Nokian Hakkapeliitta W106 winter tires and I am dogging while ridding into the office. The max recommended pressure on these puppies is 65 psi. At that pressure and with the knobs and studs my 1:20 21-mile ride now takes me 1:45. Last year I think I progressively increased tire pressure until I was running at 80-85 psi. The tires are mounted on almost new Mavic A719 rims. My question for the group is, what risks am I taking by exceeding the mfr's max pressure? Loss of bead? Sidewall blowout? Reduction of stud contact?

Thanks in advance,

Tom Moritz

electrik

Yes to all and you forgot rim-wall failure, though 85psi might not be too high(you can check online). Also you'll probably get a really bumpy and ****ty ride.

A winter commute is slower not because of studs but because of other reasons like increased effort to stay warm and cold air density which will dwarf any resistance the studs give you. Rolling resistance is about 3-5% of the resistance a cyclist faces... so look elsewhere for causes and keep the tire in shape.

bbaker22

Dunno about the risks, but my W106's beat the crap outta me at 65psi... I can't imagine running them at 80psi, unless it were a skating rink recently serviced by a zamboni.

baker

Juha

This may be true for summer riding, and there maybe some truth if riding on the ice rink served by the zamboni mentioned above. But if there's any layer of snow your riding in, rolling resistance is way, way higher. Though I suppose technically it's not rolling resistance at that point, but cutting through the snow, and so just an added component to air resistance...

+1 on not wanting to imagine higher pressure for W106s. I think I run them at max 65psi too.

--J

jollyGreenGiant

I run mine ( W106 ) at about 75 - 80 PSI and have had great results, this was a full winter last year, still waiting to put them on this year, getting close... I too felt that 65 was way too low.

tsl

I adjust my W106s to the conditions.

Using Jan Heine's articles (here and here) as a baseline, then test riding, based on my bike and my weight and I've found my W106s do best at 55F/60R in the dry.

I reduce pressure to as low as 25F/30R in really bad conditions. The increased grip is amazing, particularly in tracking. As Juha says, in really bad conditions it's not the tire causing the most rolling resistance, it's the snow and slush, so any increase in tire rolling resistance is a non-issue. The increased grip, however, is plainly evident in ruts--both hard frozen ones and packed ruts through soft snow. The bike settles down and doesn't skip side-to-side nearly as much--especially the front end.

When conditions improve, I pump 'em back up.

skijor

I religiously run my W106's at 65 psi. Yes the rolling resistance is very noticeable compared to the regular commuter tires. And I disagree with electrik, the studs do play a big part in that rolling resistance. Greater pressure = smaller footprint and more wear on the studs though the increase in risk from running at 80-85 psi vesus 65 psi would be negligible. If anything, you'd have more stud contact at higher pressure since the studs are essentially in the center.

electrik

Well, how much percentage wise does a "big part" mean? To be honest, I don't see a real need to exceed the manufacturers max psi recommendations. If you over-inflate the tire you will have less tread contact, a harsher ride and it may not even lower the rolling resistance over-all due to all the bumping around over bits of snow and ice. I don't know this w016 tire but unless the studs are exactly in the centre of the tire then the more you inflate it the less the studs will contact the ground. I doubt one would need more than 65psi to get those studs off the pavement unless you're a husky fellow.

As a side note, i think a lot of the perceived rolling resistance is just the negative effect of the heavier tire on acceleration, something which can slow you down over-all a lot more if you're stopping and starting in traffic.

skijor

I agree with "no need to exceed psi recommendations". Damn new format!....where's the effing bold and italics buttons?!?! Hell, where are ANY of the buttons? Bring back the old format!

As you can see, the W106's studs are slightly offset from center. And to reduce their contact with the ground via increased pressure would be nigh impossible. The W106's are almost the same size as a standard MTB tire. And a standard MTB tire does have noticeably less rolling resistance all else being equal.
W106 studs.jpg

electrik

Fair enough, if one can't eliminate stud to ground contact then there isn't much point to try and over-inflate. There isn't much point to over-inflating because the squirming stud is where the above "regular/typical knobby" rolling resistance comes into play...

I doubt it would be anywhere near as high as the rolling resistance from this tire though!


As long as the rider inflates the tire enough to eliminate excessive side-wall flexing(based on their weight and rim width) I doubt there are further concerns/benefits.

Wilbur Bud

I tried a few weeks at 80 psi last winter, and eventually the sidewall bulged out so I dropped back to 65. I wish they were stronger, as I'd like to be close to 90psi for most of my winter riding, which is merely cold, and rarely snow, more likely to have ice on roads here than snow, so I don't kneed the knobs so much, just the studs.

tmoritz

Well, I've gone ahead and pumped my Hakkapeliittas up to 85 psi and my transit time has dropped by 10 minutes. Still 15 minutes longer than when riding on my summer slicks. The ride is a bit squirllier but not much rougher. Stud noise is a little bit less. We'll see if I make it through the winter without blowing a sidewall. I'm not too worried about my rims. The Mavic A719 are about as tough as they come.

Thanks to all for their response. I guess we just have to grit our teeth and power through it.

electrik

Tom, https://ncrandonneur.blogspot.com/200...in-winter.html

rumrunn6

after riding yesterday my opinion is that if the OP is pumping the tires to their MAX pressure then he doesn't need studded snow tires in that width and those conditions don't warrant it. he would be better off with a narrower road tire (maybe studded). I mean if the roads are clear enough for max pressure on a wide studded tire then maybe he should be running a thinner tire. and of the roads are clear of snow then he should be using a regular road tire. (although he didn't write what size the tires were: 26" 700c?)

tmoritz

I ride 700c tires. I have a 21 mile commute to the office and even though I watch the weather forecasts very closely I've been caught in snows that arrived earlier than predicted several times in the past four years. I over pressurize my tires for a majority of my commutes but reduce pressure when the conditions get worse. I also often encounter ice on the bike paths in the morning when the temps the day before were above freezing. The worst patch is at the bottom of a hill where the path makes a sweeping right turn. I still remember the first time I encountered this ice patch! I'm glad I landed in the deep grass beside the trail.

My original question was asking about risks I was taking by over pressurizing my tires. I know I will be taking an efficiency hit with these tires. I've decided to take the risk of blowing a tire off the rim or worse causing a rim failure. I find the tires run slightly less resistance at 85 psi enough when ridden 40+ miles in a day to make it worth it. Also, on the W106's the studs are set off-center so the noise is less when riding straight so I probably have less stud wear. Again, I bleed off some pressure when the conditions warrant.

Thanks for all the input. I'll let you know if I survive the winter.

Regards,

Tom Moritz

mhifoe

I don't think there is any risk of rim failure. The Schwalbe Marathon Winter in 700c/35 is rated to 85psi.

You may be risking premature tyre failure, but it sounds like that is an acceptable risk for you to increase your ride time.