Pressures of WTB Horizon 650Bx47 tires
 

Has anyone a pointer to a table of pressures for such a tire? Barring that, a formula for their calculation. The tires have to carry a load of about 100 Kg.
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO

Pressures of WTB Horizon 650Bx47 tires
 

On Sun, 11 Nov 2018 10:29:03 -0800 (PST), Andrew Chaplin
wrote:

Has anyone a pointer to a table of pressures for such a tire? Barring that,
a formula for their calculation. The tires have to carry a load of
about 100 Kg.

I've got a smartphone app from Berto Tire (downloaded from Android
Play Store) that says for a normal road bike with 650B x 47 tires, 22
lb bike weight and 220 lbs rider, the tire pressure should be 45
psi(rear) and 32 psi (front).

cheers,

John B.

Pressures of WTB Horizon 650Bx47 tires
 

On 11/11/2018 6:03 PM, John B. slocomb wrote:
On Sun, 11 Nov 2018 10:29:03 -0800 (PST), Andrew Chaplin
wrote:

Has anyone a pointer to a table of pressures for such a tire? Barring that,
a formula for their calculation. The tires have to carry a load of
about 100 Kg.

I've got a smartphone app from Berto Tire (downloaded from Android
Play Store) that says for a normal road bike with 650B x 47 tires, 22
lb bike weight and 220 lbs rider, the tire pressure should be 45
psi(rear) and 32 psi (front).

The typical rule of thumb is to shoot for the tire to sag 15% of its
diameter when loaded. According to that, you'd want your rim to get 7mm
closer to the ground when you load up the bike. I'd just do some trial
and error with the pressures until I got that result. And I'd keep in
mind tire pressure really doesn't have to be extremely precise.


--
- Frank Krygowski

Pressures of WTB Horizon 650Bx47 tires
 

On Sunday, November 11, 2018 at 7:29:05 PM UTC+1, Andrew Chaplin wrote:
Has anyone a pointer to a table of pressures for such a tire? Barring that, a formula for their calculation. The tires have to carry a load of about 100 Kg.
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO

47 mm wide? I would say 2,5 - 3 bar to start with.

Lou

Pressures of WTB Horizon 650Bx47 tires
 

On Sunday, November 11, 2018 at 6:29:05 PM UTC, Andrew Chaplin wrote:
Has anyone a pointer to a table of pressures for such a tire? Barring that, a formula for their calculation. The tires have to carry a load of about 100 Kg.
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO

A tyre 47mm wide on a suitable rim would probably work around 2.5-3.0 bar. For comfort, I'd start on the low end and try to measure when a rim drop of about 15% of tyre diameter. I rode 60mm wide tyres with more than 100kg load (my own 95kg and 35kg of load at times) on 2 bar and down to 1.5 bar for years, and currently inflate them to about 2.4 bar and ride them down to 2.1 bar because the roads hereabouts have become worse over that period; the important consideration is not to create a fishbite and shortly a fall through a pothole.

In general, it is near-iimpossible to destroy the sidewalls of modern balloons through reasonable under inflation, so if your roads are good, start at the low-end of the spread I give and decide where you want to inflate empirically by steps and test-rides, first lower, then higher.

Andre Jute
Tyres are extremely frustrating for people with rational minds who believe everything should answer to a neat algorithm

Pressures of WTB Horizon 650Bx47 tires
 

On Sunday, November 11, 2018 at 1:29:05 PM UTC-5, Andrew Chaplin wrote:
Has anyone a pointer to a table of pressures for such a tire? Barring that, a formula for their calculation. The tires have to carry a load of about 100 Kg.

Thanks for the useful replies, gentlemen.
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO