Support road.cc

Like this site? Help us to make it better.

forum
road.cc bike forum

25mm tyres on 23 mm rims tyre pressure.

by thefatcyclist
Tue, May 19, 2020 20:34
9

Hi it has been a while.
I just replaced worn tyres with new ones and decided to up to 25mm, on my Moda road bike. The old ones had a real flat middle on the rear. I weigh 70kg the bike is around 9 kg and I frequently ride with a backpack full of groceries. say 7 kilos.
They are on and what a difference new rubber makes. But I need to decide what pressure to ride. I rode115 psi on the old ones unloaded and 120 loaded and the charts say 90 psi for the new tyres. But should I take the 23c into consideration or just ignore it.
It is riding well, but I just wanted to check.

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

Add new comment

9 comments

Avatar
thefatcyclist | 3 years ago
0 likes

Hi thanks everybody. Clear that at 90/90 I am up too high, So I will come down a bit, see how it feels, should reduce any ballooning as well but I do not see much evidence.. Thanks all. But I need to buy a decent  pressure guage, because in the heat last week the stand pump was saying I was at 105 front 100 back.

Avatar
check12 replied to thefatcyclist | 3 years ago
1 like

Digital tyre pressure gauge - https://www.wiggle.co.uk/topeak-smarthead-digital-gauge-d2/?lang=en&curr...

Avatar
Nat Jas Moe replied to thefatcyclist | 3 years ago
0 likes

With regard to the tyre pressure when the temperature goes up,  this could easily be because you inflated when it was cold and with the heat you will find an increase in pressure as air expands as you heat it up.

Avatar
iandusud | 3 years ago
2 likes

I weigh 70kg and run my 25mm tyres at 65/70 psi f/r respectively. However it does depend a bit on how you ride. Some people are "lighter" on a bike then others. What I mean is that some people are better at absorbing road shock by taking the weight off the saddle and bars as they ride over rough ground, others seem to plough through everything and are constantly getting pinch punctures unless they keep their tyres rock hard. They also give their wheels a much harder time. Learn to ride light and get the benefit of lower tyre pressures. 

Avatar
Chris Hayes | 3 years ago
0 likes

80psi should be sufficient. 85 max.  I sometimes ride with a German mate who pumps his tyres up to 130-140...never understood it.  He's fast as hell though...just nothing to do with tyre pressure! 

Avatar
Simon E | 3 years ago
0 likes

My rule of thumb for 25mm tyres: start with rider + load in kg = psi in front tyre. Add 10 psi for rear. So for you: 75 psi front, 85 psi rear (5 & 5.5 bar).

Then experiment by trying 10 psi less in each, then 10 psi more. That way you get a feel for each.

I'd not go much lower than 65, and bear in mind that if your tyre loses a few psi in between pressure checks you could be in the 50s, which would make a pinch puncture far more likely.

Avatar
bobbinogs replied to Simon E | 3 years ago
0 likes

^ what he said.

Avatar
Pilot Pete | 3 years ago
0 likes

Wow, 115psi, must have been a rock hard ride! I ride 25s and I inflate my rear to 85psi and front 80psi. Seems ok. I'm 83kg!

Avatar
CXR94Di2 | 3 years ago
0 likes

Follow the guidance, rim size isnt too important.

I ride nothing under 28mm and usually 40mm all purpose G Ones

Latest Comments