Conflicting information on new Zipp 454/404 and tire compatibility

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WonderSausage
Posts: 85
Joined: Fri Mar 29, 2013 10:51 pm

by WonderSausage

Zipp says the new 454/404 are aero optimized for 25c, but most tubeless tire vendors don't recommend 25c on wide hookless rims (I can't find an external size for the new 454 but the internal is a whopping 23mm).

For example, Zipp has Pirelli on their compatibility list, but if you go to the Pirelli site it says their 26c is not compatible with hookless. Zipp says to verify compatibility with the tire manufacturer but Pirelli says no, and Michelin and Schwalbe have no compatibility information.

Additionally, I believe the ETRTO max pressure for hookless is 73 PSI, and at 77kg I run 80 rear, 77 front on my hooked GP 5000 TLR with Roval CLX 50.

I think Zipp is prevaricating here and may put users in danger through incompatible tire choices.

Hexsense
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Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

1) For internal width, It's fine in the most case.
I use 25c Continental GP5000 on Light-bicycle AR56 which has 23mm internal width for years.
It work excellent.
I can see a problem if the tire has very narrow tread width though. But 25c Continental GP5000 and most modern tires have enough tread to abuse it this way.
2) For pressure. It's clear that Zipp intend you to upsize the tire if you exceed tire pressure limit. See figure below, if you are over 198lbs, use 28c instead.
Image
At your weight, Zipp recommend only 67-72psi in the chart (25c tire on 23mm rim ID).

Personally, I use 58-68psi on 25c tire front and 28c rear for my less than 150lbs rider weight. This is quite similar to the chart so I think the pressure this chart recommend is not bad.
3) For hookless. Well, I don't know a thing about it. So I can't answer.

by Weenie


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NLC86
Posts: 109
Joined: Fri Nov 29, 2019 2:37 pm

by NLC86

Honestly, I don't understand which guidance I should follow for tires pressure, the one provided by the wheel manufacturer (ie Zipp) or the tire manufacturer (ie Pirelli)?

TobinHatesYou
Posts: 12457
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

NLC86 wrote:
Thu Jun 24, 2021 2:11 pm
Honestly, I don't understand which guidance I should follow for tires pressure, the one provided by the wheel manufacturer (ie Zipp) or the tire manufacturer (ie Pirelli)?

The answer has always been "whichever is lower." That hasn't changed.

NLC86
Posts: 109
Joined: Fri Nov 29, 2019 2:37 pm

by NLC86

TobinHatesYou wrote:
Fri Jun 25, 2021 2:10 am
NLC86 wrote:
Thu Jun 24, 2021 2:11 pm
Honestly, I don't understand which guidance I should follow for tires pressure, the one provided by the wheel manufacturer (ie Zipp) or the tire manufacturer (ie Pirelli)?

The answer has always been "whichever is lower." That hasn't changed.
But what about the minimum pressure indicated by the tire manufacturer?

For instance Pirelli indicates that for its P ZERO Race TLR 700x28c the minimum pressure is 4.5 bar (stamped on the tire), and the optminal pressure for my weight and my rim is 5 bar (following the table reported inside the tire package).

If I use the Zipp pressure calcular, they suggest to use a pressure around 4 bar, which is below the minimum one suggested by the tire manufacturer......who is right?

TobinHatesYou
Posts: 12457
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Minimum sidewall pressures printed on tires should largely be ignored. As long as you aren’t exceeding the lower maximum indicated, you should be fine. So on something like a hookless Zipp, stick to 72.5psi max for something like a 28mm tire and I wouldn’t be inflating something like a 32psi tire that high even if the tire is supposedly rated for it.

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WonderSausage
Posts: 85
Joined: Fri Mar 29, 2013 10:51 pm

by WonderSausage

The point of my post, though, is that the wheel is "optimized for 25c" but there doesn't appear to be any compatible 25c tire, and it seems like ETRTO does not allow that combination.

Hexsense
Posts: 3270
Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

nothing new.
ETRTO guideline were ignored for years.

Remember 2013-2020?
ETRTO said if you get 17mm internal width, your minimum tire size is 25c...
All the manufacturers (except Shimano) in this period bleach it. Releasing 17mm internal width rim or wider, and say 23c is supported.

Now, ETRTO is updated in 2021. 23c can be used on even 19mm internal width according to ETRTO. That cover many use cases that once were forbidden. But it still doesn't cover 23c on 21mm internal width that were used often since 2016. It still doesn't make 23c on 21mm internal width any less usable though. It still work fine.

And once again, manufacturers still pushing the limit over what ETRTO allow. Zipp clearly push it furthest. I won't judge if it's a step too far or not. But they just do what they've done for years.

Nickldn
Posts: 1867
Joined: Mon Mar 25, 2019 12:35 am

by Nickldn

Putting ETRTO to one side and applying common sense for a moment:

17mm internal width with 23mm tyres gives you 6mm of additional tyre width, or about a third of additional tyre width.

21mm internal width with 23mm tyres gives you just 2mm of additional tyre width, or about a tenth of additional tyre width. Doesn't sound great does it?

23mm internal width with 25mm tyres also gives you just 2mm of additional tyre width, or less than a tenth of additional tyre width. Questionable.......

I guess as a rider you can make up your own mind about how lucky you feel.
Giant Propel Advanced SL Red Etap 11s Easton EC90 wheels CeramicSpeed BB Zipp SL70 bars 6.5kg

Vitus ZX1 CRS Campy Chorus 12s Bora WTO 45 disk brake wheels Zipp SL70 bars 7.5kg

SL8 build with Craft CS5060 Wheels in progress

TobinHatesYou
Posts: 12457
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

The concern is the behavior of the bead and how much downward force is being put on it when the sidewalls are “straightened” out. This isn’t about general width and rim protection concerns.

timbo43x
Posts: 5
Joined: Thu Aug 12, 2021 11:20 am

by timbo43x

NLC86 wrote:
Fri Jun 25, 2021 6:00 am
TobinHatesYou wrote:
Fri Jun 25, 2021 2:10 am
NLC86 wrote:
Thu Jun 24, 2021 2:11 pm
Honestly, I don't understand which guidance I should follow for tires pressure, the one provided by the wheel manufacturer (ie Zipp) or the tire manufacturer (ie Pirelli)?

The answer has always been "whichever is lower." That hasn't changed.
But what about the minimum pressure indicated by the tire manufacturer?

For instance Pirelli indicates that for its P ZERO Race TLR 700x28c the minimum pressure is 4.5 bar (stamped on the tire), and the optminal pressure for my weight and my rim is 5 bar (following the table reported inside the tire package).

If I use the Zipp pressure calcular, they suggest to use a pressure around 4 bar, which is below the minimum one suggested by the tire manufacturer......who is right?
I'm with you here. I'm on Zipp 303S hookless 23mm inner width. The P-Zero at 28mm state min pressure of 65psi and not to exceed 73psi on a hookless rim. This is an incredibly tight tolerance. Zipp's pressure calculator suggest that I should be riding between 58-61psi based on my weight, the tyre width, and my rim width. This is below the P-Zero pressure guideline.

Should I follow the Pirelli minimum guidelines, or assume they are not up to date for wider rim profiles?

Thanks in advance. My question is purely for my own safety.

Tim

RDY
Posts: 2356
Joined: Thu Jul 30, 2020 10:31 pm

by RDY

Simply don't use hookless if you are concerned about safety. It is never going to be without risk.

Nickldn
Posts: 1867
Joined: Mon Mar 25, 2019 12:35 am

by Nickldn

timbo43x wrote:
Mon Aug 30, 2021 9:53 am
NLC86 wrote:
Fri Jun 25, 2021 6:00 am
TobinHatesYou wrote:
Fri Jun 25, 2021 2:10 am
NLC86 wrote:
Thu Jun 24, 2021 2:11 pm
Honestly, I don't understand which guidance I should follow for tires pressure, the one provided by the wheel manufacturer (ie Zipp) or the tire manufacturer (ie Pirelli)?

The answer has always been "whichever is lower." That hasn't changed.
But what about the minimum pressure indicated by the tire manufacturer?

For instance Pirelli indicates that for its P ZERO Race TLR 700x28c the minimum pressure is 4.5 bar (stamped on the tire), and the optminal pressure for my weight and my rim is 5 bar (following the table reported inside the tire package).

If I use the Zipp pressure calcular, they suggest to use a pressure around 4 bar, which is below the minimum one suggested by the tire manufacturer......who is right?
I'm with you here. I'm on Zipp 303S hookless 23mm inner width. The P-Zero at 28mm state min pressure of 65psi and not to exceed 73psi on a hookless rim. This is an incredibly tight tolerance. Zipp's pressure calculator suggest that I should be riding between 58-61psi based on my weight, the tyre width, and my rim width. This is below the P-Zero pressure guideline.

Should I follow the Pirelli minimum guidelines, or assume they are not up to date for wider rim profiles?

Thanks in advance. My question is purely for my own safety.

Tim
I appreciate your dilemma, but let's not forget you're talking about a pressure window of about 5psi.

It's quite likely many (most) consumer tyre pressure gauges will not be accurate enough to measure the tyre pressure spot on within that range. So if you're pumping up to 65psi you may in getting anywhere between 60 - 70psi in the tyre. I expect that number may vary depending on air temperature.

There is also the pressure loss issue. If you say pump up to 65psi in the morning and go out for a long ride then you may lose 5psi throughout the day. By the time you get home you may well be on 55-60psi.

There is also the issue of fast riding, and descents, etc. It's quite likely that if you ride quickly for a few miles this will heat up the tyre and increase the air pressure inside it. A 5psi difference is entirely possible, even with disk brakes.

So what I'm really saying is the 5psi window you have presented here probably doesn't impact safety as the tyre/rim need to work in a pressure range that is much greater than 5psi. Try both, figure out which works for you and use it.
Giant Propel Advanced SL Red Etap 11s Easton EC90 wheels CeramicSpeed BB Zipp SL70 bars 6.5kg

Vitus ZX1 CRS Campy Chorus 12s Bora WTO 45 disk brake wheels Zipp SL70 bars 7.5kg

SL8 build with Craft CS5060 Wheels in progress

timbo43x
Posts: 5
Joined: Thu Aug 12, 2021 11:20 am

by timbo43x

Nickldn wrote:
Mon Aug 30, 2021 10:45 am
timbo43x wrote:
Mon Aug 30, 2021 9:53 am
NLC86 wrote:
Fri Jun 25, 2021 6:00 am
TobinHatesYou wrote:
Fri Jun 25, 2021 2:10 am



The answer has always been "whichever is lower." That hasn't changed.
But what about the minimum pressure indicated by the tire manufacturer?

For instance Pirelli indicates that for its P ZERO Race TLR 700x28c the minimum pressure is 4.5 bar (stamped on the tire), and the optminal pressure for my weight and my rim is 5 bar (following the table reported inside the tire package).

If I use the Zipp pressure calcular, they suggest to use a pressure around 4 bar, which is below the minimum one suggested by the tire manufacturer......who is right?
I'm with you here. I'm on Zipp 303S hookless 23mm inner width. The P-Zero at 28mm state min pressure of 65psi and not to exceed 73psi on a hookless rim. This is an incredibly tight tolerance. Zipp's pressure calculator suggest that I should be riding between 58-61psi based on my weight, the tyre width, and my rim width. This is below the P-Zero pressure guideline.

Should I follow the Pirelli minimum guidelines, or assume they are not up to date for wider rim profiles?

Thanks in advance. My question is purely for my own safety.

Tim
I appreciate your dilemma, but let's not forget you're talking about a pressure window of about 5psi.

It's quite likely many (most) consumer tyre pressure gauges will not be accurate enough to measure the tyre pressure spot on within that range. So if you're pumping up to 65psi you may in getting anywhere between 60 - 70psi in the tyre. I expect that number may vary depending on air temperature.

There is also the pressure loss issue. If you say pump up to 65psi in the morning and go out for a long ride then you may lose 5psi throughout the day. By the time you get home you may well be on 55-60psi.

There is also the issue of fast riding, and descents, etc. It's quite likely that if you ride quickly for a few miles this will heat up the tyre and increase the air pressure inside it. A 5psi difference is entirely possible, even with disk brakes.

So what I'm really saying is the 5psi window you have presented here probably doesn't impact safety as the tyre/rim need to work in a pressure range that is much greater than 5psi. Try both, figure out which works for you and use it.
Thanks for taking the time to write that. I work in the wonderful world of numbers and see the 'averaging' around real life thresholds and inaccuracies around these. I'll try them out and see where I settle - thank you.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

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Jackofallgrades
Posts: 250
Joined: Tue Oct 08, 2019 10:15 am

by Jackofallgrades

Reviving this, I've been looking for 25c compatible tyres. Has anyone used the Michelin Power Road in 25c? I've read that they blow up wider than some other tyres too?
Cannondale SSEvo3 'Atticus' - 7.2kg
viewtopic.php?f=10&t=161634

Cannondale Systemsix ’Dante’ - 7.7kg
viewtopic.php?f=10&t=167144

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