Am I crazy? I created the fastest 36mm tires possible.

I've put some 32 GP5000STRs on i23s and they came up just over 33. Like @Volsung I found them a bit harsh (compared to Strada Bianca 30mm tubulars), and about the same speed with slightly less grip.

pushstart wrote:I think Nooge is just looking out for safety concerns if others see this thread and want to do the same.  To avoid spiraling into the internet of arguing, probably worth highlighting that this is not advised by the manufacturer and definitely "do at your own risk".  Sounds like many factors would contribute to failure here, but probably everyone can agree that going outside the manufacturer's stated compatibility is riskier.  Similar to running unapproved tires on hookless rims, there's likely a set of parameters where this is "fine" and others where this is "downright dangerous".

Agreed, good topics for discussion!  Certainly be careful when going outside the standard parameters.    With tubless, there is a lot to consider.  I'm shocked that the industry thinks 1.1 is an acceptable factor of safety for rim blow off.    A good mfg (Schwalbe) aims for 1.6  or being able to hold 160 times the max pressure.

Fishguy wrote:Back to your original question “am I crazy?”  I would say no. It’s an interesting idea and experimenting is fun. Just be sure you are safe and around to be crazy another day. 

thanks Fishguy!

shiggy wrote:Watch out for sidewall damage, especially while cornering. The sidewall of the tire is much more exposed (as is the rim) and less able to deflect impacts.

I once mounted 32mm tires on 65mm wide rims (~59mm internal). Stayed on at 30psi. Rolled well. Was on the sidewalls and banging the rim edge in corners. 

Good point.  The tire width is ~36mm and the rim width at the tire is 35mm.   I guess that is why they recommend the wheel for 35mm and up - smaller than that and the tire would be spread too wide.   Doesn't leave much room to protect against sharp rocks.  I'm riding this on class 1, class 2 and poor chipseal surfaces mostly.  I did have a set of GP4000 on wide wheels that fit great, but I could get over onto the sidewall in a tight fast turn.  

stu wrote:I used the original GP5000 on 25 mm (inside) hooked rims for a while. They measured 34 mm wide at 50 psi with tubes.  That combination was fast and handled well but was a bit harsh on bad surfaces.  I like the 36 mm Strada Bianca better.  Someday I'll try those on my 30 mm (inside) rims but I'm not sure why.  Maybe Chas is making me crazy.  🙂

Those Strada tires sound like a better way to get to 36mm on a fast road tire.   I do like the steering response at low pressure (38 psi) when the tire isn't pinched.   I had an older set of Conti 4-seasons on the old school 19 internal rims, and the steering got pretty wonky below 50psi as the rim was just moving from side to side with the tire pinched like that.   

My SBP measure 38 mm on a 25 mm (inside) rim.  They'd probably reach 40 mm on a 30 mm rim.

yep, roughly a 2mm increase in rim width increases the tire width by 1mm (rough rule of thumb, YMMV).

I do like the steering stability I get by going as wide on the rim as possible - especially at lower pressures.

then again, I like the rim and sidewall protection from a narrower rim.   Guess that is why I have two sets of rims.  ;-)

chas wrote:@widerisfaster mentioned these: https://www.nextie.com/gravel-AGX-700C Looks like a good option ($270 for the rim).
I found the 3T wheels at something like 30% off, and still that is a crazy amount of $$$.  

I have a set of these on order. I’ll share my thoughts and findings once I’ve put some rides in. I may try the new 34mm Schwalbe Pro One on these to start. 

shiggy wrote:Watch out for sidewall damage, especially while cornering. The sidewall of the tire is much more exposed (as is the rim) and less able to deflect impacts.

I once mounted 32mm tires on 65mm wide rims (~59mm internal). Stayed on at 30psi. Rolled well. Was on the sidewalls and banging the rim edge in corners. 

This is something that I have struggled with, with the current trend of wider rims. Even the Maxxis WideTrail mtb tires often shape up poorly on my rims, and I am not pushing it (28mm internal). I put a Slaughter (one of those semislick rear mtb tires with big cornering knobs and tiny knobs on the trainstion and center tread) on a 35mm internal rim, and pulled it right off because it was completely flat across the tread, defeating the purpose of the design.

in gravel tires it is even worse. “Luckily” 2 of our bikes have 21mm internal rims, but I have a 24mm set of Hunt 650b wheels, and I bought a used bike, with some nice DTswiss wheels, but at 30mm internal, the 2.1” WTB tires had the sidewall wider than the tread, and the bike won’t clear bigger tires. A 2.0 mtb tire I set up on a 24mm internal rim has the tread quite square, and the sidewalls at least as wide as the tire.
I just mounted a Rene Herse 48mm on my 21mm rim, and it looks about perfect: tread just a hair wider than sidewalls, and nice rounded tread shape. But, really you8d want to put a 48mm tire on at least a 24mm rim.

In short, I like using fairly wide rims (although not as wide as the 29/32mm combo @chas@Chas opened with), but the tire designs have not kept up.

@Slim  

You bring up a really good point.   By going outside ETRO, you change the profile of the tread.

While this does not seem to be an issue in my specific case, it can be a big deal with knobby tires.

 With this road tire, the caution is that I could be riding on the sidewall on hard cornering (and the rubber on the sidewall of these is almost nonexistent),  With a knobby tire, its really going to affect when the side lugs get used, how they get used, how effective they are and the bike's handling

chas wrote:... By going outside ETRO, you change the profile of the tread.

The newer road tire tests on BRR include Tread/Casing Ratio.  Most tested tires run between 35% and 50%, which is a huge difference.  The various GP5000s are in the middle of that range and the various Schwalbe Pro One Addix are at the upper end.  I'd like to see that ratio included in Tour/E-Bike or CX/Gravel tire tests, I think it would be helpful for big slicks.

Regarding mounting treaded tyres on wide rims, I think it can work for slick (road tread) tyres, and for consistently treaded gravel tyres such as Schwalbe G-One or Rene Herse Knobby tyres, and not as well for semi slick tyres or tyres with should er knobs that get affected by the tyre shape.

Regarding exposed sidewalls, I have been running 31mm measured road tyres on 32mm rims, causing some sidewall exposure, and there is evidence of sidewall wear from rock strikes on light gravel. I am aiming to have a measured width of 38mmon the rim, to still have a sell behaved setup with minimal side wind impact, but less sidewall exposure than a 36mm tyre. 

Here are my candidates and their measurements by my calculations:

Pro One 34 = 38mm WAM

Override 35 = 38.4mm WAM

Cinturato Velo 35 = 38.6mm WAM

G-One Speed 35 = 38.6mm WAM

Cinturato Gravel H 35 = 38.6mm WAM

Strada Bianca Pro HTLR 36 = 38.8mm WAM

That sounds about right   I'm getting about 3-4mm wider on these rims compared to a 23 inner rim.