Rim width & tire size

[jpw]

I'm looking to have new wheels. Nothing fancy, just a pair of well built traditional wheels. Mavic Open Pro rims have a maximum recommended tire size of 28mm. I've seen a video clip of Andy Hampsten on YouTube with one of his gravel road dream bikes that have Jack Brown 33mm tires on Open Pro rims.

http://www.youtube.com/watch?v=uaOpwJbBP60

Would exceeding the manufacturer's max size recommendation of 28mm be a mistake? I have a pair of Schwalbe Marathon Racer tires in either 30mm or 35mm in mind. I'm assuming 30mm would not be too much of an issue, but would 35mm be pushing my luck?

What are the issues in play here? Is the tire in danger of coming off if oversized for the rim width?

Thanks.

[weiwentg]

I've used cross tires on Aeroheads before, and I have no reason to think that it would be a problem on something like an OP.

[phcollard]

Two weeks ago I asked Steve Hampsten if for wider tires like 33.33333mm I'd better build myself a pair of wheels with wider rims instead of Open Pro and here's what he told me: The Open Pro rims have been working just fine for me with the 33mm tires.

So I guess Open Pro is not bad :)

[AngryScientist]

at the local cross races, open pros are pretty much the most common rim siting. i'm not sure what they're reasoning is for the upper limit on tire size, but one thing is for sure: people break that rule all the time.

[RPS]

What are the issues in play here?
One possible issue based on “theory” is that when you use a larger tire the amount of force trying to separate the rim apart at the beads can be much higher if the tire is inflated to the same pressure. So if a relatively light racing rim is used with a huge tire and someone pumps the tire up to its maximum pressure it may end up overstressing the rim. Rim failure may not be immediate but could lead to faster fatigue.

In my opinion manufacturers try to take everything into account when rating equipment. When a guy does something strange he may or may not be compensating (like running lower air pressure) so he may say it works fine until someone else unknowingly tries a “similar” application and it doesn’t work out so well.

[jpw]

Thanks for the contributions thus far.

If Andy Hampsten uses a 28mm max rim and a 33mm tire without issues then I'm happy to try a 30mm tire and a 32mm tire. 35mm? Maybe I can live without that trying experiment. :-)

[CNY rider]

One possible issue based on “theory” is that when you use a larger tire the amount of force trying to separate the rim apart at the beads can be much higher if the tire is inflated to the same pressure. So if a relatively light racing rim is used with a huge tire and someone pumps the tire up to its maximum pressure it may end up overstressing the rim. Rim failure may not be immediate but could lead to faster fatigue.

In my opinion manufacturers try to take everything into account when rating equipment. When a guy does something strange he may or may not be compensating (like running lower air pressure) so he may say it works fine until someone else unknowingly tries a “similar” application and it doesn’t work out so well.

I run my studded Nokians on OP's ( I think they are 32's but don't have one in front of me right now).
Big bulky tires.
I overinflated one of them and blew it off the rim. Fortunately wasn't riding at the time. But there is a limit to what a narrow clincher rim can handle.

[Kane]

is that a wider rim would allow your tire to 'ride' more round when it is inflated.
ie. it might ride better.

In Mtn. biking wider rims are used for wider tires and the same principal holds true for road tires.
Cheers

[khjr]

is that a wider rim would allow your tire to 'ride' more round when it is inflated.
ie. it might ride better.


I asked a similar question a while ago as I'm trying to decide what rims to use for my light touring wheelset - carbon fork will limit tires to 28C, and I was wondering if there was any point in using a wider rim like the A23, Velocity Synergy (also 23 mm) etc. vs. narrower rims like the Aeroheads and Open Pros. I'd figure that if the tire was rounder in cross section, it would also be lower in height thus easier to fit under a fender in a limited clearance fork. Anyone have experience on this?

The wider rims all seem to be a LOT wider than the Open Pros, and all carry some weight penalty so, if one doesn't really need them for 30C or less, then why bother?

[jpw]

I asked a similar question a while ago as I'm trying to decide what rims to use for my light touring wheelset - carbon fork will limit tires to 28C, and I was wondering if there was any point in using a wider rim like the A23, Velocity Synergy (also 23 mm) etc. vs. narrower rims like the Aeroheads and Open Pros. I'd figure that if the tire was rounder in cross section, it would also be lower in height thus easier to fit under a fender in a limited clearance fork. Anyone have experience on this?

The wider rims all seem to be a LOT wider than the Open Pros, and all carry some weight penalty so, if one doesn't really need them for 30C or less, then why bother?

I think the OP is 15mm wide and the A719 19mm. Mavic's tire size recommendations allow for a 28mm on either rim, that being the max for the OP and the minimum for the A719.
Ideally I'd like a larger tire on a rim with a ceramic wall. Not possible, or so it seems.
My Schwalbe Marathons are a nominal 35 but an actual 33. I wonder if a nominal 30 is actually narrower?

Road racing forks don't offer much clearance. I prefer dirt road bike specs myself. Good luck.

[nicho]

I think the OP is 15mm wide and the A719 19mm. Mavic's tire size recommendations allow for a 28mm on either rim, that being the max for the OP and the minimum for the A719.
Ideally I'd like a larger tire on a rim with a ceramic wall. Not possible, or so it seems.
My Schwalbe Marathons are a nominal 35 but an actual 33. I wonder if a nominal 30 is actually narrower?

Road racing forks don't offer much clearance. I prefer dirt road bike specs myself. Good luck.
hi people,
at the home page of crossladen.de in germany one can find lots of actuall tire widths, of course it helps if you can read german. that being said they give the real width of schwalbe marathons 30 as being 28.7. if you want to go to his page click on the right hand side, "Crosslexikon" and then scroll down to capital 9, from there with a minimum of fantasy you can check the real size of a lot of tires.
good luck,
martin

knowing your weakness is a strength
i'm a weak rider, i need a light bike

[jpw]

hi people,
at the home page of crossladen.de in germany one can find lots of actuall tire widths, of course it helps if you can read german. that being said they give the real width of schwalbe marathons 30 as being 28.7. if you want to go to his page click on the right hand side, "Crosslexikon" and then scroll down to capital 9, from there with a minimum of fantasy you can check the real size of a lot of tires.
good luck,
martin

knowing your weakness is a strength
i'm a weak rider, i need a light bike

The 30 is 28.7? That's good to know.
crossladen.de - I'll take a look.
Danke Martin.

[jpw]

hi people,
at the home page of crossladen.de in germany one can find lots of actuall tire widths, of course it helps if you can read german. that being said they give the real width of schwalbe marathons 30 as being 28.7. if you want to go to his page click on the right hand side, "Crosslexikon" and then scroll down to capital 9, from there with a minimum of fantasy you can check the real size of a lot of tires.
good luck,
martin

knowing your weakness is a strength
i'm a weak rider, i need a light bike

The 30 is 28.7? That's good to know.
crossladen.de - I'll take a look.
Danke Martin.