Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Weight on a tire? Load capacity?

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Weight on a tire? Load capacity?

Reply

Old 07-14-07, 02:30 AM
  #1  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Weight on a tire? Load capacity?

(this thread will hopefully quite short - simple question, simple (hopefully) answer)

I have never really understood this piece of data, found in bicycle tire catalogues, be on paper or online. Being a light cyclist, I never paid attention, but now that I'm into tandems, I realize this figure, if not explained, makes 0 sense.

Is the weight on a bicycle tire supposed to be that of the cyclist? Of the cyclist + bike? Or just plain weight on one tire?
wroomwroomoops is offline  
Reply With Quote
Old 07-14-07, 08:47 AM
  #2  
CdCf
Videre non videri
 
Join Date: Sep 2004
Location: Gothenburg, Sweden
Posts: 3,208

Bikes: 1 road bike (simple, light), 1 TT bike (could be more aero, could be lighter), 1 all-weather commuter and winter bike, 1 Monark 828E ergometer indoor bike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The weight (load) on a bike tyre is that of approximately half of the combined weight of the bike plus the rider(s) and any equipment/cargo carried on it.
CdCf is offline  
Reply With Quote
Old 07-14-07, 11:21 PM
  #3  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by CdCf
The weight (load) on a bike tyre is that of approximately half of the combined weight of the bike plus the rider(s) and any equipment/cargo carried on it.
Well, apart from the fact that it's not correct (it's 1/3rd on the front wheel and 2/3rds on the rear), the problem I have is what the tire manufacturers mean by this figure in their catalogues? They never explain/define it. If I buy a couple of tires that has "max 145 Kg" as stated in the catalogue or manu's website, does that mean a 145 Kg heavy rider will be able to use them but not a 160 Kg one? Or does it mean that the weight on one wheel should not be over 145 Kg? In which case even a 200 Kg rider can safely use them...

Last edited by wroomwroomoops; 07-16-07 at 10:44 AM.
wroomwroomoops is offline  
Reply With Quote
Old 07-15-07, 12:17 AM
  #4  
CdCf
Videre non videri
 
Join Date: Sep 2004
Location: Gothenburg, Sweden
Posts: 3,208

Bikes: 1 road bike (simple, light), 1 TT bike (could be more aero, could be lighter), 1 all-weather commuter and winter bike, 1 Monark 828E ergometer indoor bike

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Originally Posted by wroomwroomoops
Well, apart from the fact that it's not correct (it's 1/3rd on the front wheel and 2/3rds on the rear)
Depends on the bike, but for a road bike, it's closer to 50/50, maybe 40/60.
CdCf is offline  
Reply With Quote
Old 07-15-07, 04:33 AM
  #5  
JeanCoutu
ǝıd ǝʌol ʎllɐǝɹ I
 
JeanCoutu's Avatar
 
Join Date: Apr 2007
Posts: 518
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Man I was hoping someone would give a better reply to this...

Well, ok so I'm fairly light too and this used to never have been an issue, but last year I had an ebike that weighed a massive 42kg, and I weighed 70-ish. So total that together and you get 112kg right? Well, for a while the rear tire was a Schwalbe Big Apple 26X2.0, it was mounted on a 1" ish wide rim, and Schwalbe rates this tire at 125Kg. It was inflated just over the max sidewall pressure of 70psi. And, well it was OK but marginal, a bit more and things like going up a good sidewalk lip at speed would have snakebitten it, and going off curbs was something I avoided though I did it a few times and it didn't get nuthin.

My conclusion is that the weight they rate tires for is the total bike + rider weight.

Last edited by JeanCoutu; 07-15-07 at 04:39 AM.
JeanCoutu is offline  
Reply With Quote
Old 07-15-07, 07:59 AM
  #6  
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 31,112

Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1007 Post(s)
Originally Posted by wroomwroomoops
Well, apart from the fact that it's not correct (it's 1/3rd on the front wheel and 2/3rds on the rear), the problem I have is what the tire manufacturers mean by this figure in their catalogues? They never explain/define it. If I buy a couple of tires that has "max 145 Kg" as stated in the catalogue or manu's website, does that mean a 145 Kg heavy rider will be able to use them but not a 160 Kg one? Or does it mean that the weight on one wheel should not be over 145 Kg? In which case een a 200 Kg rider can safely use them...
That's interesting. I've never seen a load rating on a bike tire. The only number, other than size, I've ever seen is the maximum inflation pressure in psi or bar. What make and model are you seeing this on?

The load rating would be per tire, just as it is for automobile and truck tires.
HillRider is offline  
Reply With Quote
Old 07-15-07, 11:20 AM
  #7  
JeanCoutu
ǝıd ǝʌol ʎllɐǝɹ I
 
JeanCoutu's Avatar
 
Join Date: Apr 2007
Posts: 518
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Some load ratings:
http://www.schwalbetires.com/node/61/ok
JeanCoutu is offline  
Reply With Quote
Old 07-15-07, 03:30 PM
  #8  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by HillRider
That's interesting. I've never seen a load rating on a bike tire. The only number, other than size, I've ever seen is the maximum inflation pressure in psi or bar. What make and model are you seeing this on?

The load rating would be per tire, just as it is for automobile and truck tires.
Both the Schwalbe and the Continental catalogue quote the load/weight on a tire (or is it on "a" tire? that's my question - is it the weight of the rider + bike?).

Should I post a scanned page from the catalogue, or will you trust my word for it?
wroomwroomoops is offline  
Reply With Quote
Old 07-15-07, 03:37 PM
  #9  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by JeanCoutu
Man I was hoping someone would give a better reply to this...

Well, ok so I'm fairly light too and this used to never have been an issue, but last year I had an ebike that weighed a massive 42kg, and I weighed 70-ish. So total that together and you get 112kg right? Well, for a while the rear tire was a Schwalbe Big Apple 26X2.0, it was mounted on a 1" ish wide rim, and Schwalbe rates this tire at 125Kg. It was inflated just over the max sidewall pressure of 70psi. And, well it was OK but marginal, a bit more and things like going up a good sidewalk lip at speed would have snakebitten it, and going off curbs was something I avoided though I did it a few times and it didn't get nuthin.

My conclusion is that the weight they rate tires for is the total bike + rider weight.

Getting a straight answer is like a breath of fresh air. Thanks JeanContu!

By the way, I'm a big fan of the Big Apple tires, got them on two of my bikes (one is a 700C commuter/occasional "MTB", the other is a urban assault/occasional "commuter"). You might want to upgrade to the 26X2.25", should be much better against snakebites. My problem is a slightly bit greater, as I'm looking for a solution for a tandem. If I crash, I'm okay with it, but I would really hate to have my friend go down, too. I care a bit more for her than for my thick skin.
wroomwroomoops is offline  
Reply With Quote
Old 07-15-07, 06:10 PM
  #10  
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 31,112

Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1007 Post(s)
Originally Posted by wroomwroomoops
Should I post a scanned page from the catalogue, or will you trust my word for it?
Easy man, I just said I've never seen the data, not that it didn't exist.
HillRider is offline  
Reply With Quote
Old 07-15-07, 10:03 PM
  #11  
jur
Senior Member
 
Join Date: May 2005
Location: Melbourne
Posts: 7,401
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 308 Post(s)
It seems fairly straightforward to me: A given tyre has a maximum pressure rating, based on the cascass strength. Air pressure is what keeps the tyre material in a loop from one rim will to the other wall. You can imagine a tyre being composed of strings under tension looping from one wall to the other.

A loaded tyre will deflect those strings locally, until the extreme case where the rim squeezes the looped tyre to the ground. Ergo, a given maximum pressure equates to a maximum load.

Presumably, manufacturers also factor in a certain amount to allow for road irregularities without pinching the tyre between rim and road.
jur is offline  
Reply With Quote
Old 07-15-07, 10:59 PM
  #12  
ken cummings
Senior Member
 
ken cummings's Avatar
 
Join Date: Dec 2005
Location: northern California
Posts: 5,603

Bikes: Bruce Gordon BLT, Cannondale parts bike, Ecodyne recumbent trike, Counterpoint Opus 2, miyata 1000

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Not to worry. Those limits have a huge margin of safety otherwise Santana and others could not be turning out 3, 4, and 5 person bikes. I have read that the tire pressure that will blow a tire off its rim is about double the recommended pressure. The total weight on my tandem's tires of a 50+ lb bike, gear, 260+ wife and 205+ captain works out to ~250 lb per 26"x 2" Specialized tire at the sidewall stated 65 PSI. Works fine
ken cummings is offline  
Reply With Quote
Old 07-15-07, 11:05 PM
  #13  
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Posts: 28,321

Bikes: 1987 Bianchi Campione

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Does it even matter what the weight on the tire is? You have a max recommended pressure. If you are overloading it, the tire will blow off before you can get it to an acceptable pressure while maintaining rideability..?
operator is offline  
Reply With Quote
Old 07-16-07, 03:32 AM
  #14  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by operator
Does it even matter what the weight on the tire is? You have a max recommended pressure. If you are overloading it, the tire will blow off before you can get it to an acceptable pressure while maintaining rideability..?
It matters, because as you said, you can pump the tire up to a maximum pressure (now whether this is the one stated on the sidewall, or is it higher than that because the manu adds a large safety margin, is immaterial to this point), and you have to see how much weight can you put on the tire before it pinch-flats. If the tire construction allowed for higher pressure, you could put more weight on it before it pinches. And whether it will pinch at a given pressure and weight, also depends on the size of the tire. The bigger the tire's cross section, the more weight you can put on it.
wroomwroomoops is offline  
Reply With Quote
Old 07-16-07, 03:34 AM
  #15  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by ken cummings
Not to worry. Those limits have a huge margin of safety otherwise Santana and others could not be turning out 3, 4, and 5 person bikes. I have read that the tire pressure that will blow a tire off its rim is about double the recommended pressure. The total weight on my tandem's tires of a 50+ lb bike, gear, 260+ wife and 205+ captain works out to ~250 lb per 26"x 2" Specialized tire at the sidewall stated 65 PSI. Works fine
Which one is that tire, is it one of the Armadillos?
wroomwroomoops is offline  
Reply With Quote
Old 07-16-07, 09:22 AM
  #16  
Mr. Underbridge
Senior Member
 
Join Date: Mar 2007
Location: Reston, VA
Posts: 2,369

Bikes: 2003 Giant OCR2

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Originally Posted by operator
Does it even matter what the weight on the tire is? You have a max recommended pressure. If you are overloading it, the tire will blow off before you can get it to an acceptable pressure while maintaining rideability..?
Indirectly, it might matter. One might want to have an idea of the weight distribution on the front vs. back, to have an estimate of how much to unbalance the pressure to get similar contact patches on both tires. Right now, I run 95 psi front / 105 psi rear. That seems to work for me, but it's a bit guesswork.

If I have the time and get sufficiently obsessive about it, I might try to measure the front or rear contact patch. I figure putting some ink or something on one tire and riding over a piece of paper might get me close.
Mr. Underbridge is offline  
Reply With Quote
Old 07-16-07, 09:44 AM
  #17  
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Posts: 9,438

Bikes: Trek 5500, Colnago C-50

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Originally Posted by CdCf
Depends on the bike, but for a road bike, it's closer to 50/50, maybe 40/60.
I'm pretty sure a loaded road bike will be more like 40/60 or 35/65 based on the disproportionate tire wear. I run about 118 psi in the back and 105 in the front.

Al
Al1943 is offline  
Reply With Quote
Old 07-16-07, 10:40 AM
  #18  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by HillRider
Easy man, I just said I've never seen the data, not that it didn't exist.
Good, 'cause I just don't happen to have either catalogue at hand
wroomwroomoops is offline  
Reply With Quote
Old 07-16-07, 03:55 PM
  #19  
jur
Senior Member
 
Join Date: May 2005
Location: Melbourne
Posts: 7,401
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 308 Post(s)
Originally Posted by Al1943
I'm pretty sure a loaded road bike will be more like 40/60 or 35/65 based on the disproportionate tire wear. I run about 118 psi in the back and 105 in the front.

Al
Rear tyres wear more not because of more loading but because of micro-slipping. Front wheels just roll along untill you start braking.
jur is offline  
Reply With Quote
Old 07-16-07, 04:27 PM
  #20  
urbanknight
In beaurocratic limbo
 
urbanknight's Avatar
 
Join Date: Mar 2006
Location: Los Angeles, CA
Posts: 22,456

Bikes: Specialized Allez, K2 Razorback

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
My understanding is that the load rating is for that total weight on THAT TIRE ALONE, including the weight of the bike, rider(s), and accessories. My car, for example, has tires rated for about 1000 lb, but there are 4 tires and the car plus occupants and cargo usually weighs 3100-3500 lb

I don't know if I agree with the comments that a road bike is distributed 50/50. If that was the case, why does my front tire barely even bulge at the bottom while the rear bulges out plenty?
__________________
"Well, I guess you can cut the arts as much as you want... Sooner or later, these kids aren't going to have anything to read or write about." (Richard Dreyfus as Glenn Holland)
urbanknight is offline  
Reply With Quote
Old 07-16-07, 08:57 PM
  #21  
wroomwroomoops
Sir Fallalot
Thread Starter
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Posts: 5,277
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Originally Posted by urbanknight
My understanding is that the load rating is for that total weight on THAT TIRE ALONE, including the weight of the bike, rider(s), and accessories. My car, for example, has tires rated for about 1000 lb, but there are 4 tires and the car plus occupants and cargo usually weighs 3100-3500 lb

Thanks for a straight answer, urbanknight. Too bad it diametrically differs from what JeanCoutu concluded.
wroomwroomoops is offline  
Reply With Quote
Old 07-16-07, 10:05 PM
  #22  
urbanknight
In beaurocratic limbo
 
urbanknight's Avatar
 
Join Date: Mar 2006
Location: Los Angeles, CA
Posts: 22,456

Bikes: Specialized Allez, K2 Razorback

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Originally Posted by wroomwroomoops
Thanks for a straight answer, urbanknight. Too bad it diametrically differs from what JeanCoutu concluded.
Well my experience is from cars, so I won't be hurt if you go with his conclusion.

edit: Anybody care to solve the dispute about weight distribution?
__________________
"Well, I guess you can cut the arts as much as you want... Sooner or later, these kids aren't going to have anything to read or write about." (Richard Dreyfus as Glenn Holland)
urbanknight is offline  
Reply With Quote
Old 07-17-07, 10:07 AM
  #23  
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Posts: 9,438

Bikes: Trek 5500, Colnago C-50

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Originally Posted by jur
Rear tyres wear more not because of more loading but because of micro-slipping. Front wheels just roll along untill you start braking.
Do you have a technical reference for micro-slipping and tire wear?
Al1943 is offline  
Reply With Quote
Old 07-17-07, 10:10 AM
  #24  
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Posts: 9,438

Bikes: Trek 5500, Colnago C-50

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Originally Posted by urbanknight
Well my experience is from cars, so I won't be hurt if you go with his conclusion.

edit: Anybody care to solve the dispute about weight distribution?
I would assume that bike tire weight limits work the same as motor vehicles and trailers, each tire has its limit. The total weight is divided proportionate to the weight on each wheel.
Al1943 is offline  
Reply With Quote
Old 07-17-07, 10:21 AM
  #25  
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 31,112

Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1007 Post(s)
Originally Posted by Al1943
Do you have a technical reference for micro-slipping and tire wear?
No technical references but plenty of empirical observations.

As an experiment, weigh two brand new identical bike tires and install them on your road bike. Ride the bike until the rear tire is totally wasted with the cords showing. Examine and weigh both tires at that point. You will find 1) the front tire shows no visible tread wear and 2) the front tire weighs within a couple of grams of it's new weight while the rear has lost considerable weight.

A poster on a different bike forum has done a fairly extensive study by doing the above experiment on numerous sets of tires and concluded that front tires don't wear significantly at all even after several thousand miles while rear tires wear very noticeably in much less distance. I've done the before-and-after weighings on a couple of sets of tires too and reached the same conclusion.

That doesn't mean front tires last forever. They do age and flex harden and the rubber gets more brittle and cut prone from exposure to light and heat.
HillRider is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service