Tire Height/Profile HELP!

[cornelldewitt]

Hang on, this is a long one.

I rode Conti Super Sport 28mm tires for the better part of two decades on a 1991 Serotta. Love them--nice ride, and I live in NYC and never got a flat. Plus, they were the biggest tires I could squeeze on to my Davis Phinney (I'm also old, so I like bigger tires.) I've always avoided the Gator Skin tires 1) because they reportedly use a harder rubber compound and so the traction is apparently compromised, especially in wet conditions--no thank you-- and 2) see above--I'd never gotten a flat on the Super Sports.

Then they discontinued the Super Sports. So I bought a pair of Conti Grand Prix 4 Season 28mm tires. Popped them on and, man, the clearance between the top of the tire and the rear brake was TIGHT--WAY less clearance between tire and brake than the Super Sport, but they still fit, so I didn't give it too much thought.

Rode a couple hundred miles, and LOVED them--much better ride than the Super Sports. Although seemed more prone to tiny rocks & leaves getting stuck between the tire & brake with such tiny clearance. (This is just on the rear tire, fork has much more clearance.)

Recently I rode on the roller trainer for a little while, and by the end of the ride, the top of the tire was rubbing the brake. The only thing I can figure is that over time, or due to the heat of the metal rollers, the tire broke-in, or warped ever so slightly and expanded by about half a MM or so--just enough that it now rubs the brake. Argh!

Pop off that tire and put an old Super Sport 28 on the rear wheel. Still fit great. Throw the old calipers on it, and it turns out the Conti Grand Prix 4 Seasons 28mm tire is THREE MILLIMETERS TALLER than the old Super Sport 28mm tire. WHAT?!

Inflated to about 85psi (did I mention I'm old) the Super Sport 28 is 24mm from outside of rim to top of tire; the Grand Prix 4 Seasons is 27mm.

I tried to tell my wife that clearly the only solution is that I need a new bike, but she didn't buy it. And no, I'm not going to just get 25mm tires. Don't be fatuous. I've ridden 28mm on this bike for decades and I'm only getting older. Weird, but true.

So my question is, does anyone have any experience with the HEIGHT of the Grand Prix tires? Anyone have Grand Prix 5000 tires on their bike they can throw calipers on and check the height?

Any insight on tire height in general? Anyone recommend 28mm tires that are closer to 24 or 25mm in height? Lower-profile tires, generally?

Thank you for listening!

[AngryScientist]

Good morning.

What rims are you using? Rim width will have a real effect on tire profile. I'm guessing you're likely on "vintage" generation 19mm external width rims.

[Nessism]

Tires of different brand and model, are different height and width, despite being labeled the same.

For example, the Conti GP 4000 is wider and taller than the GP 5000. I think there was implementation of ISO 5775 at some point, to try to standardize the sizing.

[MikeD]

Why not try GP 4 Seasons 25mm width? Tire width is proportional to height so finding a 28mm wide tire that's 25mm in height is not going to happen unless you are using very wide rims which distorts the tire profile.

[spoonrobot]

Originally Posted by MikeD

Why not try GP 4 Seasons 25mm width? Tire width is proportional to height so finding a 28mm wide tire that's 25mm in height is not going to happen unless you are using very wide rims which distorts the tire profile.

OP has shared his preferred tires tires that were 28mm wide are 24mm tall and were consistent for two decades. So obviously, they exist.

After experiencing a ton of pinch flats on tires that were 37mm wide but only 33mm tall, I used Bicycle Rolling Resistance to find tires that were relatively tall for their width. It would also work to find tires relatively short for their width.

Here are two I found, both 2023 models.
(Measured width on a 17.8 mm inner width rim, at an air pressure of 100 psi / 6.9 bar)
28w/25h
https://www.bicyclerollingresistance...ro-race-tlr-28
28w/24h
https://www.bicyclerollingresistance...er-agilest-tlr

I've found tire height to be less consistent than width, across all tire types.

[RoosterCogset]

Originally Posted by Nessism

Tires of different brand and model, are different height and width, despite being labeled the same.

For example, the Conti GP 4000 is wider and taller than the GP 5000. I think there was implementation of ISO 5775 at some point, to try to standardize the sizing.

Yup. There can be large differences between different models of the same nominal size.

[fourflys]

Looks like maybe you need to try some GP5k’s? Should be able to find for a decent price in 28mm clincher I bet.. if you want to stick with Conti anyway.. I have some 28mm Vittoria Corsa Controls I can measure when I get home.. clinchers with latex tubes mounted on Hed Belgiums.. they fit great on my SL4 Roubaix (2012ish?)..

[Peter P.]

Originally Posted by cornelldewitt

...Inflated to about 85psi (did I mention I'm old) the Super Sport 28 is 24mm from outside of rim to top of tire; the Grand Prix 4 Seasons is 27mm...

Sorry not to answer your question directly, but from the statement above, I'd suggest you try a Grand Prix 4 Seasons 25mm tire. It may measure oversize and be closer to the max clearances you're looking for.

[cornelldewitt]

You guys are amazing--way more info and help than I thought I'd get.

A couple further details and thoughts.

I did swap tires when I swapped wheels: I was on period-correct Campy Lambda rims, which are about 19mm outside width, and switched to not-quite period-correct Campy Neutron wheels (couldn't resist), which are about 21mm outside. So theoretically, the 4 Seasons probably would never have fit to begin with on the old rims.

In spite of my preference for 28mm, it did occur to me--per MikeD's and Peter P's suggestions--that 25mm 4 Seasons would have the same height as my old 28mm Super Sports, so might deliver a similar ride feel (and durability, etc) to what I liked about the 4 Seasons. So that's a good option.

It is also good to know that the GP 5000 seem to have a very low profile for the 28mm width--I'm just not sure about the durability and all-weather traction of them. That being said, it does appear that they are probably more of a hybrid successor/replacement of the old Super Sports.

Also, thanks to spoonrobot for the referral to Bicycle Rolling Resistance--I'll definitely play around with that to explore different options, and Panaracer never occured to me. I'm hesitant to put P-Zeros on for day-to-day riding here in NYC.

Thanks again, all. And...

SEPP KUSS!!!!!!

[Wunder]

I only used Super (not Ultra) sports once like a decade ago. From what I recall they were wire bead, crazy stiff, and HEAVY (like 400g for a 23). It’s possible that because if that stiffness they held a much more rigid shape as opposed to a 4season which is comparatively soft.

What was the WIDTH of the 4 season relative to the Super Sport in a labeled 28. I would also recommend trying a 25 4 season, or ultra sport, or even a gator skin. From what I recall the Supers were terrible.

[cornelldewitt]

Originally Posted by Wunder

I only used Super (not Ultra) sports once like a decade ago. From what I recall they were wire bead, crazy stiff, and HEAVY (like 400g for a 23). It’s possible that because if that stiffness they held a much more rigid shape as opposed to a 4season which is comparatively soft.

What was the WIDTH of the 4 season relative to the Super Sport in a labeled 28. I would also recommend trying a 25 4 season, or ultra sport, or even a gator skin. From what I recall the Supers were terrible.

You're definitely not the first person to point out that the Super Sports were not great--I dunno, they just worked for me, and yes, they were wire bead, stiff, and heavy. Probably all good reasons Conti discontinued them. But they were 28s that fit on my bike! Good question re width, because yes, the Super Sport 28s also measured in at under 27mm width, whereas the 4 Seasons 28s measured in at just over 28mm wide--almost 2mm difference between the two.

Given that the height and the tread/compound on the 4 Seasons is what gave me the ride I liked (while it lasted), and I'm not super fussed about the width, I'm giving serious thought to trying the 25mm 4 Seasons. But the GP5000 28mm may be the first thing I try, just to try something totally different.

[gravelreformist]

I would not get too hung up on what width is printed on the sidewall. As you are discovering, the effective width depends on the specific tire/rim combination. Currently manufacturers appear to be updating their stated widths to reflect real-world widths on contemporary equipment. This may mean that an old 25mm tire and a 'new' 28mm from the same manufacturer might be the same tire.