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What is an acceptable deviation tolerance for actual tire weight from the mean/advertised?
I received 2 tires of the same spec and one is 3% overweight and the other is 8% overweight.
That’s completely normal. There can be enormous variation in tire weight from tire to tire, even when they are identical models. Some hardcore puzzlers will weigh out tires with a gram scale at the store to get the lightest ones possible. I have never, ever, ever been able to tell a 7% difference in mountain bike tires because they’re so damn heavy to start with.
Here’s a fun one: get a measuring tape and angle finder and go measure the geometry on your current bike. I guarantee you it doesn’t line up with the geometry chart. At least one number will be surprisingly off.
Not being able to feel approx. 100 g difference on the outside of a rotating wheel?
Fun fact: in my puzzling experience do Maxxis tires not differ much, while Schwalbe have huge deviations between identical models/compounds/sizes.
There was an interesting podcast with Nino Schurter's mechanic on pinkbike (yes, you can actually write that name and say you visit the site on this forum...). He claims that he gets batches of tyres at the start of the season, weighs them all and separates them into light/normal/heavy, they mostly use the normal ones, heavy ones come out for rocky courses. They don't use the light ones because the weight suggests there might be a flaw or imbalance in them, that was the most surprising revelation!
pretty normal variation in the manufacturing process. given that tires can't be reworked once they're molded, i would assume they have a pretty wide tolerance range on the weight spec, assuming there even is a spec on weight in the first place.
unless you're comparing them side by side on identical bikes with identical wheels, it's practically impossible to tell the difference in that little weight (~3.5oz for non-metric folks), unless it isn't evenly distributed. we're talking about less than 10% on just the tire, and that percentage drops when you add in the weight of the rim, nips, tube/sealant, inserts (if used).
On my bike, it would be less than 0.6% of the total bike weight. I certainly wouldn't notice that. I mean, I've added extra sealant weighing that amount and not noticed it.
Yeah, 100 grams of rotating mass sounds like a lot, but generally speaking, I think it's really hard to identify what I'm feeling and where it's coming from on a bike. I think I could probably notice a 100 gram difference in tires if it was a front wheel and we did back to back testing with the same bike, same trail, and same wheels on the same day, and that's if you told me we were testing tire weight. But if you did blind testing and didn't tell me what change to be looking for, I'm not sure I would know it's a rotating mass thing. I might think it's a head angle/fork offset/steering thing. If it's a rear wheel, I don't think I could feel the difference unless I was on a very light and very short travel bike. On an enduro bike, there's just too much stuff moving around in space at the back of the bike to perceive little things like that.
And without being in a "product testing mindset," I think there's zero chance I would put on a new tire like normal and think during my ride "Man, this tire feels heavier than advertised, and/or heavier than the tire it replaced." The only way I would ever notice that is if I'd already measured tires on a gram scale first, and that's because in my mind I'd unconsciously be looking for evidence to confirm my bias.
Here's a funny thought: every tire I've ever replaced is likely lighter than the new tire replacing it, because the knobs are shaved off and worn down on the old one. But I've never noticed the change in rotating weight. I notice the change in grip and support from having fresh knobs and stiff casings.
One last thought, since we're already nerding out. Aluminum rims weigh +/- 500 grams, double butted spokes and brass nipples are +/- 200 grams per wheel, and then you've got 75 grams of sealant or so. Leaving out hubs, rotors, and cassettes because they're centrally located, your total rotating mass per wheel with a 1200 gram tire is almost 2000 grams. That means your 100 gram change in tire weight is less than a 5% change in total rotating mass. If you throw in a hub, rotor, and cassette (300g, 200g, 400g), your change in wheel weight is more like 3%. That's a pretty small delta to notice on a bike where things are constantly squishing and bobbing and turning and absorbing.
If you've spent a few hours researching light weight parts and then dropped significant coin on said parts it's not completely out of line to be picky about tire weight deviation. I wouldn't notice 50-100g of extra tire weight while riding but it does show up on the scale and small gains throughout the bike add up.
yea, the weight does add up. but the point is you're not gonna notice that difference in rotational weight without direct side by side comparisons. and i don't think they could hold tighter weight tolerances without significant increases to cost (if that's even possible with the manufacturing process without just resorting to drastic increases in scrap rate). most people I know are already balking at $100/tire MSRP.
Some comments here.
Worn vs. new tire: from weighing them, a worn tire usually loses 15-40 g (26", 2.4/2.5). Because your sealant most likely has partially dried up, most of the weight addition comes from fresh sealant.
Rotating weight: the farther on the outside of a wheel, the more you will feel the weight from a ride dynamic point of view. So saving 100 g on the hub won't be noticed much, but on the tire it will. Weight reduction on the hub will be noticed when you consider suspension action though, because unsprung weight.
I think you are right, during "normal" riding 100 g difference in tire weight is less noticable than e.g. on a road bike, because it is a smaller part of the total weight. However, during climbing, pumping the bike through rollers, quick direction changes and especially jumping I think it is noticable quite a bit.
I think it is funny that people that argue that they feel a difference between clicks on their suspension settings also tell me they cannot feel a weight reduction in a tire. I would go on and argue that both are very much noticeable and even have an influence on each other.
What you report from Nino’s mechanic is representative of where my mind was at when I brought up this topic; it would be interesting to be able to infer from weight, if the tire would be more or less durable or if weight does not correlate. I think it is hard to speculate with my small sample, but coming from him, he has been through enough tires to draw some conclusions. So, thanks for sharing!
(edited to add “‘s mechanic” after Nino)
Right now I'm doing my senior mechanical engineering project on a subject related to this. I'm measuring a tire's effective spring rate and seeing how it changes with tire construction, with the goal of using it as a tuning parameter in addition to internal pressure. Obviously this is for the pointy end of the spear in terms of rider skill; mainly aiming at pro teams to use the info/device during pre-season testing. In the research process I was lucky enough to connect with a WC mechanic and tire weight inconsistency is just the tip of the iceberg. The person I spoke with said he has a durometer tester since the durometer of a batch of tires can vary by up to 8a, which in some cases can be upwards of 20% off compared to the claimed value. We spoke for like an 40 minutes about how inconsistent tire manufacturing is, and to complicate it more how some of those values might not matter. A prime example was the modern crop of Conti tires; they don't feel soft and grippy when you squeeze them, but in use are among the best dry/intermediates out right now. Something about the construction (casing, tread, etc..) provide a lot of mechanical grip despite having harder rubber. Long story slightly less long...for the average person chasing consistency in tires is an uphill battle and a topic that is super complicated that even WC DH teams are struggling to cope with. If you like to nerd out, go for it, otherwise what you can actually feel on a trail might be in your head. Despite my unrelenting bitterness towards TeamRobotKillsYourFace shutting down to pursue "a real career" and collectively making mountain biking worse by not regularly posting the onslaught of informed, hateful, and hilarious diatribes to keep the masses in check, I agree with Charlie. From what the Furbees tell me, Charlie is a skilled rider that has functional knowledge of how a bike behaves and most importantly why it behaves the way it does. Most people probably can't identify small changes like deviations in tire weight since most people aren't tuned in enough or consistent enough in their riding to be able to isolate those changes.
Going from EXO casing Maxxis tyres (Assegai/DHR2) to Michelin Racing Line Wild Enduros, I can't say I noticed the weight at all. The bike rides about the same in regards to liveliness, pop and the like.
It's much slower going up and on smooth downs though as the tyres have a MUCH higher rolling resistance. That I did in fact notice. Immediatelly. I mentioned in another thread (tech rumors?) that ideally I'd like to test the same compound with two wildly different casings (EXO vs. DH casing on 3C MaxxGrip), but it'd be best to have a power meter to confirm that. Even the Michelin experience is only anecdotal, but is confirmed by multiple people trying out my bike and swapping over, especially going from mine to another bike is a WORLD of difference. Plus easily being chased down smooth, straight trails by friends while deathgripping, having to pedal on slight descents while people just roll besides me going the same speed, etc.
But the grip man... the grip... :O
Sounds like an interesting senior project! I've always wondered about tire spring rates, especially whether a tire's spring rate is measurably progressive, like an air spring in a fork, or if it's practically perfectly linear because it's such a small displacement into such a large overall volume. I've also wondered how massive tire inserts like Cushcore change the spring rate or progressiveness of tires as they take up so much volume. Would love to see your final work when it's done.
Something interesting about the Continental tires is that they use 120tpi casings instead of 60tpi, which is very unusual for a DH tire. Higher TPI counts (120, 220, 320, etc) are known to be more supple, but 60tpi is kind of the gold standard for DH tires because fewer threads per inch also means thicker threads, meaning more cut resistance. Continental is obviously doing something special to protect the thinner threads in the casing, and if they can protect the casing without compromising the supple casing, maybe they can have a grippier casing than the competition. For instance, I believe a Double Down tire is two layers of 120tpi (like a Continental), which makes it noticeably more supple but gives much less cut resistance than a dual 60tpi Maxxis DH casing tire.
And thanks for the kind words about TEAM ROBOT. Glad you enjoyed it. Was always a blast to write.
Conti is doing some really interesting things with their compounds and constructions. They use a much firmer compound as a very thin top layer that covers the ooey-gooey compound inside. Getting good deformation from the soft compound interior but increased durability from that outer layer.
Interesting, the complete opposite to what everybody else has been doing - soft rubber on the surface to grip the ground with a harder rubber inside to provide stability to the knob...
I did exactly what you are talking about a long time ago. Maxxis Minion 2.5 42a, one standard DH, one UST version. UST version was folding and therefore around 140-160 g lighter. Both set up tubeless on Mavic 823 rims with sealant. The weight loss was totally noticeable.
I wonder how they keep the knobs from folding.
The weight difference is even higher these days. But I'm more interested in the rolling resistance - do you retain the awesome grip of a soft compound but have a faster rolling tyre? Or is the resistance not related to the carcass as much as the compound is.
Thats cool! I've been working on measuring & collecting tyre data, and testing what I can to see the differences in casing, compound and age. Going to take a while to get enough useful data think its and area that is woefully underestimated at the moment, so will be interested to see what you find!
i had the same tyres being 1100gr and 1300gr, soft super trail magic mary 29x2.4 i find this quite annoying as if im getting a 1.3kg tyre i would also love it to be at least a super gravity tyre, not a super trail ( nothing wrong with the latter but not at SG weight )
Just XC tires, but some look like the same carcass/different compound or the other way around:
https://www.bicyclerollingresistance.com/mtb-reviews
I noticed that on the conti's, more specifically the kryptotal and argotal, that the knobs even though they are higher than usual , they don't deform and wiggle as much as assegais on slick rock under pressure, they seem much firmer but the grip on my opinion is much better than anything from Maxxis.
I recently bought three kenda hellkat pro 27.5 and there was 50g difference from lightest to heaviest. Doesn’t sound like a lot, although it’s on the outer edge of rotating mass so there’s a greater chance it would be noticeable in a tire vs something like a 50g heavier dropper post. I imagine it would make a difference in a professional XC race, but for my purposes it’s just fine.
I think you're more likely to notice the weight of the tire if your climbs are typically difficult and rough and you have to continually be accelerating the mass to deal with trail irregularities. If you're just spinning up a fire road, you'll not notice the extra mass because you don't have to accelerate it as much. I feel it important to minimize rotating weight out at the rim/tire.
Yes and no - I find that lighter tyres need to be pumped up more to factor in the lighter casing, which means you deflect off features far more than a heavier, lower pressure casing, which can conform to said features and make it easier to maintain momentum (the key to technical climbing imo).
I went from WTB Vigilante/Trail Boss Tough tyres to XC (for a charity ride) and honestly I noticed the lack of conformity and grip more than the weight savings. But they sure do roll well on fire roads!
I can't speak to XC-type tires since those don't work for me, but the difference between a heavy DHR2 and a light DHR2 is noticeable when you're reaching the exhaustion point of your "I've been climbing non-stop as long as I can" run.
Out of curiosity, how much climbing are you talking about?
Ha, asking someone online about their climbing volume is like asking how big was the fish they caught
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