Conti GP5000 28 actual width on 21C and 25C rims

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igs417
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by igs417

Anyone out here measured actual width of Continental GP5000 TL 700x28C tires on 21C or 25C rims, around 80 psi?

by Weenie


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pdlpsher1
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by pdlpsher1

GP5K 28s on 21C rim measures exactly 30mm.

bm0p700f
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by bm0p700f

25c rims are too wide for these tyres. So are 21c rims. The top of the tyre is to flat and it will square off faster. I know I am talking to the wind here but its the truth.

dim
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by dim

bm0p700f wrote:
Sat May 25, 2019 9:11 pm
25c rims are too wide for these tyres. So are 21c rims. The top of the tyre is to flat and it will square off faster. I know I am talking to the wind here but its the truth.
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bm0p700f
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by bm0p700f

just because it not a popular view does not make it wrong. I have tried these tyres on wide rims and they seem to be made for 17 to 19mm internal width rims. If the crown of the tyre is flat then the tyre is mounted on rim that's too wide for it.

I have not mounted the 32mm tyre yet. My point is not about safety but how the tyre performs and wears. It is possible to make a 28mm tyre to fit just right on a 21mm internal width rim but the thread thickness would need to vary in such a way that it would be wrong in a 17mm internal width rim. So what rim width do you think continental has in mind.

Ask conti what rims widths they suggest for there tyres.

Theres no need to be rude either.
Last edited by bm0p700f on Sat May 25, 2019 10:20 pm, edited 1 time in total.

TobinHatesYou
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by TobinHatesYou

I had no issue with the GP5Ks squaring off on wide rims. In fact the two wear indicators on my first set were almost gone and they still didn't square off.

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Dan Gerous
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by Dan Gerous

My GP5000 are 700x25 so even narrower and still, their crown are perfectly round on rims with 21c internal width, it would be surprising if the 28 would be too stretched out.

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Beaver
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by Beaver

bm0p700f wrote:
Sat May 25, 2019 10:01 pm
just because it not a popular view does not make it wrong. I have tried these tyres on wide rims and they seem to be made for 17 to 19mm internal width rims. If the crown of the tyre is flat then the tyre is mounted on rim that's too wide for it.

I have not mounted the 32mm tyre yet. My point is not about safety but how the tyre performs and wears. It is possible to make a 28mm tyre to fit just right on a 21mm internal width rim but the thread thickness would need to vary in such a way that it would be wrong in a 17mm internal width rim. So what rim width do you think continental has in mind.

Ask conti what rims widths they suggest for there tyres.

Theres no need to be rude either.
Have you experienced any negative aspects in riding 25mm tires on 21mm internal width rims with low pressure?

Aren't all tires flat on the ground when under load?

The Conti GP 5000 width is now given on 19mm internal rim width btw.

Sometimes one has to reconsider one's point of view, maybe it's not that one is the only sane person left in the world. ;)

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Valy
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by Valy

I have not had experience with this directly, but would not the tire have more material to wear off before becoming squared off on a wider profile? As well as if the wear area from straight line travel is wider, would not it require a shallower angle of lean to keep the wear even.

MikeD
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by MikeD

ETRTO table:
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Hexsense
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by Hexsense

MikeD wrote:
Fri May 31, 2019 9:48 pm
ETRTO table:
Leave it die. It is universally treat as obsoleted standard.

Mavic once zealot about stricting to ETRTO standard. They bashed every other company who violate it.
Then year passes, they breaking it too, saying new standard is in the making for modern rims, so ignore ETRTO...

Campagnolo also violate it now in WTO line. So almost no one strict to ETRTO at this point. The only one who still base their recommendation tire size on ETRTO is Shimano. But we all know how far behind Shimano clincher is to everyone else.


ETRTO table was created when tire were wire bead (no kevlar) with lousy tolerance of both alloy rims and tire manufacturer in year 19xx. No tight tubeless rim+ tight fit kevlar bead tire back then.

It error way in the caution side, rather than potential performance gain of using narrow tire on wide rim.

MikeD
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Joined: Thu Dec 11, 2014 9:55 pm

by MikeD

Hexsense wrote:
MikeD wrote:
Fri May 31, 2019 9:48 pm
ETRTO table:
Leave it die. It is universally treat as obsoleted standard.

Mavic once zealot about stricting to ETRTO standard. They bashed every other company who violate it.
Then year passes, they breaking it too, saying new standard is in the making for modern rims, so ignore ETRTO...

Campagnolo also violate it now in WTO line. So almost no one strict to ETRTO at this point. The only one whose still base their recommendation tire size on ETRTO is Shimano. But we all know how far behind Shimano clincher is to everyone else.


ETRTO table was created when tire were wire bead (no kevlar) with lousy tolerance of both alloy rims and tire manufacturer in year 19xx. No tight tubeless rim+ tight fit kevlar bead tire back then.

It error way in the caution side, rather than potential performance gain of using narrow tire on wide rim.
Why is a narrow tire on a wide rim a performance gain?

Hexsense
Posts: 770
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

In essense, it create effectively wide tire, without some down side of wide tire.

1.) large tire narrow rim can feel squishy in corner at low pressure. Wide rim base but narrow tire is opposite of that, you can lower a lot of pressure and gain comfort without feeling that tire got pushed sideway in hard corner.
2. Aero, side wall is more vertical than bow in and out. Create smoother transition.
3. Wide effective tire with weight of narrower tire. Worth nothing that rolling resistance is based on effective tire width not stated tire width. Bigger rim with more air volume also gain small tire the rolling resistance upgrade.

What it do worse than actual wide tire:
Flat protection. Tire thread and casing still is narrow. More part of sidewall get used as center thread in corner.

by Weenie


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