Author Topic: 28mm tyres that aren't undersized - what exists?  (Read 1963 times)

FifeingEejit

  • Not Small just Far Away at the back
Re: 28mm tyres that aren't undersized - what exists?
« Reply #25 on: December 25, 2018, 09:45:51 pm »
Not carried out with a control tyre... or with a particularly accurate pressure gauge... or any scientific control at all really...
All tyres in a state best described as "well used"

Gp4season 28mm
On Hunt 20mm internal:
31.7mm at 70psi,
31.8mm at 80psi
and 32.2mm at 90psi

On Mavic 17mm internal:
29.2mm wide at 80psi
and 29.8 at 90psi

Gp4season 25mm
On shimano rs81 15mm internal width
26.7 at 60psi
27mm at 70psi
27mm at 80psi
27.1mm at 90psi



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Re: 28mm tyres that aren't undersized - what exists?
« Reply #26 on: December 27, 2018, 12:21:45 am »
I purchased some 28mm Conti 4 Seasons just over a year ago.  After 7000k on Alexrims DF23 rims at 85psi they are 30mm width.  The rims are supposedly 16mm internal width although I measured about 15.5mm.

Very interesting - this shows Continental must have changed its 4Season sizing and corroborates my recent sighting, so thanks.


85psi in 30mm tyres would be far too uncomfortable for me, though - I'd probably have them at about 50psi as road surfaces are so bad where I ride.

Re: 28mm tyres that aren't undersized - what exists?
« Reply #27 on: December 27, 2018, 12:36:03 am »
some tyres are just made the wrong size, no doubt about it.

Continental is atrocious with its sizing accuracy/consistency, making right-sizing for one's clearances when making purchases a complete lottery - hence my queries about field measurements of the GP 4Season.

The original Continental '32mm' Top Contact measured about 27mm wide (and that was to the outside edge of the side lugs), whilst the '28mm' GP4000S II measures 29.5mm wide on the same rim.  The '37mm' Top Contact Winter just scrapes over 31mm wide. Boneheads!!

Re: 28mm tyres that aren't undersized - what exists?
« Reply #28 on: December 27, 2018, 12:40:06 am »
Not carried out with a control tyre... or with a particularly accurate pressure gauge... or any scientific control at all really...
All tyres in a state best described as "well used"

Gp4season 28mm
On Hunt 20mm internal:
31.7mm at 70psi,
31.8mm at 80psi
and 32.2mm at 90psi

On Mavic 17mm internal:
29.2mm wide at 80psi
and 29.8 at 90psi

Gp4season 25mm
On shimano rs81 15mm internal width
26.7 at 60psi
27mm at 70psi
27mm at 80psi
27.1mm at 90psi

Thanks for going to the trouble of measuring - I'm sure others will find this useful too.

The data from yourself and JonBuoy for the 28mm GP 4Season is most encouraging, so I shall be ordering some forthwith.