Measured Width of Conti GP 4000S II Tires

[Splash]

Hello all.

I measured the inflated (95psi) width of these tires on my bike (and installed on the new Zonda 25mm rims).

I purchased these tires in the advertised 25mm width in the expectation that it would better match the 25mm rims.

I measure 27.01mm at the top of the tire. This is the maximum width as it reduces somewhat as you go further down towards the rim.

I have read that these particular tires tend to be wider than the advertised width. Is this correct?

I am concerned that I now have a wider tire than what I wanted with that light bulb effect / profile on the rim.

If i bought a 25mm wide tire, what should the width at the top of tire be when measured in the inflated state?

Are there other advertised 25mm tires that measure 25mm at the top of the tire, when inflated?

What is the disadvantage of the tire being wider at the top of the tire than at the base of the tire sitting in the rim?


Splash

[kramnnim]

Yes.

Depends on the width of the rim.

Sure.

Rubs some frames.

[Splash]

I have searched the internet and unable to locate the rim section dimensions of the C17 rim. Can someone possibly please provide these dimensions - depth, outer, inner, etc.?

What should the top width of an 25mm tire be to suit this particular rim given these dimensions?

What are some of the other brand tires in the 25mm clincher that measure 25mm at the top when inflated?



Splash

[CiclistiCliff]

buy the 23mm version and you'll be fine.

[cadence90]

i have searched the internet and unable to locate the rim section dimensions of the c17 rim. Can someone possibly please provide these dimensions - depth, outer, inner, etc.?
Splash
Campagnolo Zonda C17
Rim internal width: 17.0mm
Rim external width: 22.5mm
Milled rim differentiated height: 24-27mm (front) and 27-30mm (rear)

[Llewellyn]

Splash

It's 2mm - not much of a "light bulb effect"!! You'd barely notice it. They are a great riding tyre, just get out there and ride the s**t out of them.

[Splash]

Thanks Guys.

When a rim manufacturer states that their rim suits 25mm tires, what part of the tire is this diemnsion referring to?


Splash

[sitzmark]

buy the 23mm version and you'll be fine.

This. My 700x23 GP4Ks2 measure 25mm on 24.7mm (brake track) rims. Don't recall bead hook width. IIRC they also measure close to 25mm on a 20mm rim.

[simonov]

Splash

It's 2mm - not much of a "light bulb effect"!! You'd barely notice it. They are a great riding tyre, just get out there and ride the s**t out of them.

This. They're great tires and will ride great on those rims as long as there are now clearance issues.

They're also tires that are generously sized. The 23s would probably match up more closely to some other brands' 25s. And as cadence called out, the rims aren't 25mm, they're 22.5mm. So most any brand's 25 is going to create that "lightbulb" effect, not that there's anything wrong with that. 23s would be a better match for the gentle curve you're probably looking for.

That said, I ride wide rims, skinny rims, wide tires, skinny tires, and in all different combinations and given the right pressures the differences are not as dramatic as the magazines would have you believe. Good tires ride well. Crap tires don't. The rest is pretty close to splitting hairs.

[Tony T]

See: http://www.slowtwitch.com/Products/Things_that_Roll/Training_Wheels/Ardennes_long_term_review_4056.html

http://www.slowtwitch.com/articles/images/3/86683-largest_Comparison_small.jpg

Unfortunately, it is difficult to say exactly how much your tire will ‘swell’ due to the wider rim. As we’ve discussed many times in the past, the size listed on your tire label isn’t always accurate to begin with – and they must make that label assuming a given rim size.

[Tony T]

Here's 23mm and 25mm GP4000's on a 25mm HED Ardennes+ rim:

[oldpotatoe]

Hello all.

I measured the inflated (95psi) width of these tires on my bike (and installed on the new Zonda 25mm rims).

I purchased these tires in the advertised 25mm width in the expectation that it would better match the 25mm rims.

I measure 27.01mm at the top of the tire. This is the maximum width as it reduces somewhat as you go further down towards the rim.

I have read that these particular tires tend to be wider than the advertised width. Is this correct?

I am concerned that I now have a wider tire than what I wanted with that light bulb effect / profile on the rim.

If i bought a 25mm wide tire, what should the width at the top of tire be when measured in the inflated state?

Are there other advertised 25mm tires that measure 25mm at the top of the tire, when inflated?

What is the disadvantage of the tire being wider at the top of the tire than at the base of the tire sitting in the rim?


Splash

None, no disadvantage in actual terms of your riding performance. Frame/fork/brake/chainstay clearance is what's most important and reliability.

Also I think 95psi is too high of a pressure for you.

[fignon's barber]

If you're looking for a "smaller"25mm tire, get Veloflex 25mm. They are the same size as a gp4000s 23mm.

[djg21]

Hello all.

I measured the inflated (95psi) width of these tires on my bike (and installed on the new Zonda 25mm rims).

I purchased these tires in the advertised 25mm width in the expectation that it would better match the 25mm rims.

I measure 27.01mm at the top of the tire. This is the maximum width as it reduces somewhat as you go further down towards the rim.

I have read that these particular tires tend to be wider than the advertised width. Is this correct?

I am concerned that I now have a wider tire than what I wanted with that light bulb effect / profile on the rim.

If i bought a 25mm wide tire, what should the width at the top of tire be when measured in the inflated state?

Are there other advertised 25mm tires that measure 25mm at the top of the tire, when inflated?

What is the disadvantage of the tire being wider at the top of the tire than at the base of the tire sitting in the rim?

Splash

Go ride your bike! You're over thinking it.

[kramnnim]

Go ride your bike! You're over thinking it.

This x 10

[Splash]

Also I think 95psi is too high of a pressure for you.

what psi on front and rear would be better?

Splash

[djg21]

what psi on front and rear would be better?

Splash

Again. Go ride your bike. Maybe try some different pressures and see what you like?

[Tony T]

what psi on front and rear would be better?

Splash

Depends on your weight. For a 160-180 lb rider, I'd say 80psi (many go to 75psi), but since you're now at 95, I'd suggest dropping 5 psi for a start, then try another 5psi drop to see how you like it.
Since the front carries less weight, I have 5psi less in the front than the rear.

…and if your on the East Coast, its too cold to ride :)

[djg21]

Start here maybe:

https://silca.cc/blogs/journal/118616068-part-2-tire-stiffness-wider-is-stiffer-harsher

[John H.]

I just measured a couple different continental tires- both have some miles on them.
1.) Conti GP4000 II 700x25 mounted on a Hed Belgium (standard width)- 28mm.
2.) Conti GP4000 II 700x28 mounted on a Belgium Plus disc rim- 32mm.

Safe to say that the 700x28 GP4000 will not fit a lot of bikes that say "max tire size 700x28".

[cadence90]

…and if your on the East Coast, its too cold to ride :)

I think Splash is from this place (https://www.youtube.com/watch?v=XfR9iY5y94s).

[Llewellyn]

I think Splash is from this place (https://www.youtube.com/watch?v=XfR9iY5y94s).

In Adelaide I think - nice place. Plenty of big hills around there too.:banana:

[Tony T]

…and since it's almost Summer there, then yes, he should just go out and ride :)

[Splash]

close..... I live in Melbourne, Victoria... :-)

SPLash

[estilley]

I rode my bike today with GP 4000s ii today.

I don't know what the pressure was.

I don't know what the measured width is.

I had fun!

[oldpotatoe]

what psi on front and rear would be better?

Splash

'Better' is tough but I use 85psi, front and rear, whether it be 25mm tubulars or 25mm clinchers. Last clincher was Conti GP 4 season, 28mm(measured about 25mm on DT 585, for info), also at 85 psi..I'm .1 offa ton rider as well, got no pinch flats.

[JStonebarger]

I just measured a couple different continental tires- both have some miles on them.
1.) Conti GP4000 II 700x25 mounted on a Hed Belgium (standard width)- 28mm.
2.) Conti GP4000 II 700x28 mounted on a Belgium Plus disc rim- 32mm.

Safe to say that the 700x28 GP4000 will not fit a lot of bikes that say "max tire size 700x28".

Yeah, our "28mm" GP4000IIs measure >31mm on Velocity A23s, and only fit our 'cross bikes. That said, the ride is glorious.

http://www.bicyclerollingresistance.com/specials/conti-gp4000s-ii-23-25-28

[fignon's barber]

close..... I live in Melbourne, Victoria... :-)

SPLash


Do you know the Maven? That guy is awesome.

[Splash]

Hi Fignon - Sorry I do not know Maven.


SPlash

[Splash]

Thanks Guys.

When a rim manufacturer states that their rim suits 25mm tires, what part of the tire is this diemnsion referring to?


Splash

[John H.]

I am going to say that these are all approximations and averages.
There are no standards.

As you can see a 25mm Conti measures 28mm-
28mm Conti measures 32mm-

You pretty much need to take try the intended rim with the intended tire in the bike and see if it fits-

Thanks Guys.

When a rim manufacturer states that their rim suits 25mm tires, what part of the tire is this diemnsion referring to?


Splash

[cp43]

Thanks Guys.

When a rim manufacturer states that their rim suits 25mm tires, what part of the tire is this diemnsion referring to?


Splash

My understanding is that rim widths typically refer to the outside width. So, the 19, 23, and 25 in the pic that Tony T posted.

As far as tire size, unless it's rubbing on your frame, just ride, and don't worry about whether or not the measured size matches the nominal size.