Author Topic: gp5000 vs gp4000: 32 vs 28 mm declared size  (Read 1184 times)

gp5000 vs gp4000: 32 vs 28 mm declared size
« on: February 26, 2019, 11:52:50 pm »
In case it's of use to others ... Just taken some 28 mm gp4000s off to put on some 32 mm gp5000s, and thought I'd measure.  The rims are Pacenti Forza.

So note -- gp4000s have about 6000 to 8000km on them, and have a reflex band, which might add .5mm

gp4000 28 mm Front / Back

60 psi    32.7 / 32.5
80 psi    32.9 / 32.7
100 psi  33.2 / 33.4

gp5000 32 mm Front / Back after 24 hours

60 psi    32.5 / 32.7
80 psi    33.1 / 33.3
100 psi  33.3 / 33.3

Take away  -- the old 28 were bigger than specified, the new 32 are on the money, and you won't get much benefit in size from the 32s.  (This probably helped gp4000s in rolling resistance tests.)  And -- as I remember, shortly after going on the gp4000s were measuring 31; but that's a vague memory.

Re: gp5000 vs gp4000: 32 vs 28 mm declared size
« Reply #1 on: February 27, 2019, 09:14:05 am »
SO, they just updated the tyre size markings to match the ACTUAL size.  ::-)

Still, good to know. Thanks.

Re: gp5000 vs gp4000: 32 vs 28 mm declared size
« Reply #2 on: February 27, 2019, 09:43:44 pm »
SO, they just updated the tyre size markings to match the ACTUAL size.  ::-)
Either that, or they changed their assumption of what size rim the tyres would be used on :)