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Conti GP5000 28 measures 26

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Conti GP5000 28 measures 26

Old 02-09-22, 11:08 PM
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Symox
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Conti GP5000 28 measures 26

Just replaced a Gatorskin 28 with a GP5000 28 and was surprised how much skinnier the new tire looks. I measured both at the same pressure with the same tube. The Gatorskin measured 28mm whereas the GP5000 was 26mm. Not that big of a deal, but I feel like I could fit a GP5000 32 if it scales the same.

Anyone have a 32 or 30 GP5000 you could measure the width of?

Also, why is there such a discrepancy from the same company. Is it the sidewall strength?

Thanks
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Old 02-09-22, 11:18 PM
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ofajen
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Originally Posted by Symox
Just replaced a Gatorskin 28 with a GP5000 28 and was surprised how much skinnier the new tire looks. I measured both at the same pressure with the same tube. The Gatorskin measured 28mm whereas the GP5000 was 26mm. Not that big of a deal, but I feel like I could fit a GP5000 32 if it scales the same.

Anyone have a 32 or 30 GP5000 you could measure the width of?

Also, why is there such a discrepancy from the same company. Is it the sidewall strength?

Thanks
Conti is following the newer ETRTO standards for expected rim width. The standards expect tires to be on wider rims, so they adjusted tires to produce roughly nominal width on the wider rim, meaning the new versions run narrower on skinnier rims.

Otto
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Old 02-09-22, 11:31 PM
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Originally Posted by ofajen
Conti is following the newer ETRTO standards for expected rim width. The standards expect tires to be on wider rims, so they adjusted tires to produce roughly nominal width on the wider rim, meaning the new versions run narrower on skinnier rims.

Otto
Thanks for the info. I have 19mm rims (Mavic Open Pro), is there a way to calculate expected widths?
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Old 02-10-22, 05:30 AM
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Wow. I have an two year old 5000 28mm and on a 19mm rim it measures 29mm at 90psi. On a 25mm rim it measures 31mm. Yes the tire manufacturers need to publish width on at least one rim. I guess they sell more tires that way.
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Old 02-10-22, 06:34 AM
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I have a 28mm GP 5000 measuring 26.9 mm on a rim where a 28mm GP4000 used to measure 30.5 mm and a 25 mm used to measure 27.5 mm. These are tubed versions. I am left wondering if I should order 28 mm with the new GP 5000 S tubeless version. I can fit 27.5 mm on my bike but not like over 28.5 mm. At 100 bucks a pop, they could easily show width for 17, 19, and 21 mm internal width to the rim (not the external width). The 25 and 23 GP5000 are almost the same width on 19 mm internal rims
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Old 02-10-22, 06:35 AM
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Originally Posted by Symox
Just replaced a Gatorskin 28 with a GP5000 28 and was surprised how much skinnier the new tire looks. I measured both at the same pressure with the same tube. The Gatorskin measured 28mm whereas the GP5000 was 26mm. Not that big of a deal, but I feel like I could fit a GP5000 32 if it scales the same.

Anyone have a 32 or 30 GP5000 you could measure the width of?

Also, why is there such a discrepancy from the same company. Is it the sidewall strength?

Thanks
It depends on your rim width and the tire pressure. Calculations are made with specific ones and it will vary from a rim to another.

My previous Cadex 700x25c tires have the same width than my current Schwalbe 700x28c tires. Some are known to be ''truer to size'' than others.

Last edited by eduskator; 02-10-22 at 06:38 AM.
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Old 02-10-22, 06:52 AM
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It's like orange juice. Used to come in 1/2 gallon containers (64oz), now it comes in 52oz containers. It's to help hide the fact that cost has gone up; they just give you less but charge the same.
WHATS UP WITH ORANGE JUICE?

On a serious note, it seems weird and undesirable if Conti really changed their tire sizing on an existing production model without at least renaming it slightly like v2 or something.

Last edited by Sy Reene; 02-10-22 at 06:55 AM.
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Old 02-10-22, 07:03 AM
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Originally Posted by Symox
Thanks for the info. I have 19mm rims (Mavic Open Pro), is there a way to calculate expected widths?
Is that the interior or the exterior width? 19 mm interior would be reasonably wide.
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Old 02-10-22, 07:19 AM
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Others have already touched on the reasons for discrepancy. If you're trying to maximize your available clearance, it can be frustrating. To make things easier, some manufacturers have adopted and published WAM and RAM specifications (Width/Radius as Mounted), but Conti has been conservative, lagging well behind the leaders in the market.
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Old 02-10-22, 08:18 AM
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Originally Posted by alcjphil;[url=tel:22405074
22405074[/url]]Is that the interior or the exterior width? 19 mm interior would be reasonably wide.
19mm internal width
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Old 02-10-22, 08:22 AM
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Originally Posted by Symox
19mm internal width
Keep them well inflated and measure again in a few weeks. I wouldn't be surprised if there's a bit of stretch over time.
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Old 02-10-22, 10:10 AM
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Worth noting that Conti has 3 versions of this tire. Tubed, Tubeless (TL) and Tubeless/hookless compatible (S TR). I have used all three in various widths, and all measure differently.

Currently:
28mm GP5000 with tubes @80psi on a 23mm external carbon rim (I'm guessing 18-19mm internal but I've never measured) = 26.2mm actual

28mm GP5000 S TR w/o tubes @60psi on a 27mm external/23mm internal hookless carbon rim = 27.8mm actual

I have a set of 32mm TL's, not currently mounted, but I had these on a 19mm i.d. alloy rim last summer and recall them being slightly less than actual 32mm size.
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Old 02-10-22, 10:19 AM
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Originally Posted by msu2001la
Worth noting that Conti has 3 versions of this tire. Tubed, Tubeless (TL) and Tubeless/hookless compatible (S TR). I have used all three in various widths, and all measure differently.

Currently:
28mm GP5000 with tubes @80psi on a 23mm external carbon rim (I'm guessing 18-19mm internal but I've never measured) = 26.2mm actual

28mm GP5000 S TR w/o tubes @60psi on a 27mm external/23mm internal hookless carbon rim = 27.8mm actual

I have a set of 32mm TL's, not currently mounted, but I had these on a 19mm i.d. alloy rim last summer and recall them being slightly less than actual 32mm size.
weird considering BRR's comparison chart:

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Old 02-10-22, 06:31 PM
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Originally Posted by Symox
Just replaced a Gatorskin 28 with a GP5000 28 and was surprised how much skinnier the new tire looks.
Like ​ofajen said it is the new ETRTO standard. If you think installing GP5K 28 mm in a 19C rim is surprising, imagine mine when I installed GP5K 25 mm in a 17C rim. But the tires do grow wider after a few cycles of pre-ride inflation and riding.
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Old 02-10-22, 10:14 PM
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Originally Posted by SoSmellyAir
Like ​ofajen said it is the new ETRTO standard. If you think installing GP5K 28 mm in a 19C rim is surprising, imagine mine when I installed GP5K 25 mm in a 17C rim. But the tires do grow wider after a few cycles of pre-ride inflation and riding.
That is good to hear. I'll monitor the width over time.

Part of me wants to order the 32mm versions based on how skinny these are (hoping they match the 28mm width of the Gatorskins) - I like me some wide tires
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Old 02-10-22, 10:25 PM
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Its funny, after a day of full inflation, it is measuring 27mm. I rechecked the Gatorskins, which are slightly more than 27mm but *look* wider for some reason.

Weird.

I'll shut up and ride now
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Old 02-10-22, 11:48 PM
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Originally Posted by Symox
That is good to hear. I'll monitor the width over time.

Part of me wants to order the 32mm versions based on how skinny these are (hoping they match the 28mm width of the Gatorskins) - I like me some wide tires
But that would not be aero, so you must just HTFU.
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