Dictatorsaurus

I'm running older carbon Renolds 46/66 clincher wheels with 14mm internal width. With the older GP4000 25C tires, the actual measured tire width was 26mm. With the new GP5000 28c tires, the measured width is 25mm which is disappointing.

Is it worth trying to go with the 30C GP5000 hoping for a tire where the width will be more than the current measured 25mm?

Bald Paul

Reifen_Felgenkombinationen_EN.pdf (schwalbe.com)

Dictatorsaurus

That chart doesn't answer my question. Looking for feedback on 14mm internal rim and actual tire size. Not theoretical size.

Bald Paul

Well, if you're looking for opinion, rather than recommendations of an actual tire manufacturer, my answer is .........


Maybe. Maybe not.

datlas 

Not sure running wide tires on a very narrow rim is a good idea, is it?

Dictatorsaurus

I think manufacturers say with 14mm internal width you can go up to 35C.

What it will actually measure as is the mystery.

Iride01 

Won't be a mystery if you try them out. Will it be a disaster if they are off by a few millimeters? Personally I doubt it. If it is, then it's just that tires ride quality or whatever compared to another model of tire. Or just your own high expectation.

Pressure too might also affect the width you measure. So if you are running significantly lower tire pressure than the manufacturer might recommend if you find their chart tables or calculator tool for recommended tire pressure at your ride weight, then I can see where it might measure narrower.

mstateglfr 

But if the 'wide' tire ends up being the same width and height as the older 'narrow' tire, is that really running a wide tire on a very narrow rim?

GhostRider62

GP4000 25 mm were big (27-29mm depending on which rims I used)

GP5000 25 mm run nominal on "normal rims", skinny on your rims as can be seen with your 28mm running 26mm.

I have all those sizes and from memory I would guess 30 mm GP5000 tubes on narrow internal rims are going to be 27.5-28.5 mm. Depends on tire pressure and age, too.

30mm tubeless on wide internal hookless run 31-32 and 32mm run 34.5mm after breaking in

Dictatorsaurus

My exact thoughts!!!!

tFUnK

No experience with the exact configuration but I would guess that a 30mm will measure out to ~28mm ish on an old school narrow rim.

I went through a similar situation as I have newer wider rims on some bikes and older narrow rims on other bikes. I've found the old 25mm Conti GP4k tires on 23mm external rims to be 26-27mm, which just fits my older frames. The new GP5ks I've read run narrower due to compensating for modern wider rims.

I found that I can maybe run 28mm tires on narrow rims, or I can run 25mm tires on wider rims. But 28mm tires on wider rims for sure won't clear any of my road frames.

So I basically stick to 23-25mm tires on modern rims and 25 tires on older rims.

biker128pedal

I’d buy one tire and try. I have some data of a 25mm GP5000 on a 14 mm rim at it measured 25.6mm at 115 psi after stretching. This was a tire when o bought when they first came out. Not tubeless.

I have a newer about a year old non tubeless 28mm. On a 19mm rim at 90psi it measured 29mm. I did not try it on the old 14mm front wheel I don’t use anymore. Wanted to but did not take the time.

My guess is get a 30mm. It would end up 27 to 28 is my vote.

Dictatorsaurus

I just ordered a 30C GP5000. I would be happy if it measures 27mm-28mm on my 14mm internal width rims.

I'll report back once I get it and install it with the actual measurements.

msu2001la

My first MTB had 2" wide knobby tires installed on 15mm ID rims.
It'll be fine.

Dictatorsaurus

As promised. Here are the measurements:

14mm inner width rim:

- GP5000 clincher 28 - Measures 26mm
- GP5000 clincher 30 - Measures 28mm

Basically, the tire measures 2mm less than the advertised width on narrow 14mm rims.

I installed the 30 up front and the 28 on the rear since the rear would not allow for a wider tire.

Iride01 

GP 5000's come in quite a few slightly different versions of clincher. Which did you get?

Camilo

I read somewhere, or maybe dreamt, that some tire companies are now assuming a wider rim when they label the tire widths on their tires.

For example, if previously a typical road rim internal width was 14mm, they'd label a 700cX25 tire that way expecting it to be about 25mm when inflated on a typical rim. It might have plumped up a couple mm on a wider rim back then. Isn't that why we all started thinking about getting wider rims back then before they were common? To get a little more volume from the tires we were using? (23 or 25 typically)

If nowadays they're assuming that a typical rim is now wider, maybe 18 or even 20 internal width, they might label a tire as 28 even though it might be essentially the same tire as that previous 25, because they assume it's how it will measure on that new typical rim. If it's mounted on what they now assume is an atypical narrower rim, for example, a 14mm rim, it might end up being just like the "old 25" on that rim, still measuring 25mm give or take instead of the label size of 28mm.

I don't know if this is a fact or just a dream I had. But it kind of makes sense.

RJC1811

That sounds like a reasonable explanation. I had assumed it was shrinkflation, like a bag of chips where they don’t raise the price just give you less product. However it seems like the prices have gone up as well. Good info! I have some 28mm GP5000 to go on my Defy (17mm rims) but I want to wait until it’s off the trainer. First to reduce wear on the rear tire but also I want a good before and after comparison when I put the new tires on.

Dictatorsaurus

I have no idea! I got the expensive version!

The 30C weighed around 250g.

Camilo

Always the best idea!

aliasfox

One additional thought - how fresh was the GP5k when you measured it? If it's freshly mounted, I'd give it a day or two at-pressure to settle in before measuring. Maybe even leave the bike outside in the sun to allow the tire to 'relax' a bit.
All of my tires, from 23mm to 32mm, always look just a little... shy... when first mounted.

Dictatorsaurus

The tire expended maybe 0.5mm after a few rides.

Chandne

They definitely resized the 5000s. I stocked up on some 4000s while I could. One set of 25s on 19.5mm internal-width rims measure 28.38 and 28.42 today. On my older 18mm rims, they still measure 28.

79pmooney

Do you have a bike shop that carries Continental? I'd go in and tell them you want an actual 28c for your rim; that you would like to try a 30c but wold like to be able to bring it back if it doesn't measure out. Good shop, this shouldn't be an issue.

Dictatorsaurus

Read post #15.