Z900RS

Please login or register.

News: A big welcome to all new members !


Author [NL] [FR] [ES] [DE] [SE] [IT] [NO] [MY] Topic: Tire Pressure  (Read 8017 times)

0 Members and 1 Guest are viewing this topic.

Offline Travelman

  • Z900RS Member
  • **
  • Posts: 18
  • Bike: Z900RS / FJR1300
  • Town / City: South Shields
  • Country: gb
Re: Tire Pressure
« Reply #40 on: May 14, 2019, 07:58:24 AM »
I sometimes donít check pressures for weeks, riding by the Ďfeelí. Manufacturers recommended pressures are a decent starting point, but can never possibly suit all weights and riding conditions. I can tell when I need extra air, even which tyre if itís just one, and I donít obsess about the actual read out. So far itís worked!

Offline RetroZ

  • Z900RS Member
  • **
  • Posts: 81
  • Bike: Z900rs
  • Town / City: Glasgow
  • Country: scotland
Re: Tire Pressure
« Reply #41 on: May 15, 2019, 10:03:54 AM »
I found a link yesterday, can't find it now {this might be it https://www.motorcyclenews.com/news/2000/august/its-important-to-be-pumped/) , but it explained that tyre companies all recommended different pressures for different tyres and conditions until a few years ago. Then, all the motorcycle tyre manufacturers agreed to build tyres designed to be operated at a standard 36 & 42psi, in all conditions. Also found the following advice...................

"Finally, what I would advise against, is running tyres outside the recommended settings. We, GoodYear, spend a great deal of time designing, developing, testing, productionising and evaluating tyre performance, as you can imagine; there is a substantial amount of data related to this that we have at our disposal and this varies across tyre ranges and vehicles/vehicle types. However, what the evidendce always confirms is that running tyres outside of the recommended pressure, is dangerous as it can lead to separation, splits, and catastophic failure as a result of the tyre's natural flexing and tolerances, going out of spec.  Be cautious of the internet which is awash with "I run at..." and whilst this might "work" it is dangerous for the reasons given and is not something we would ever recommended. You may get "lucky" and have never experienced a problem, but if the tyre does fail due to incorrect pressure, and at high speed, then of course this is likely to be more serious!! Instead, and for motorcycles, the rider should ensure tyres are set to the recommended pressure (36/42psi) and look to adjust the suspension over a period of trial, to compensate for riding style, road conditions, weather, etc. AND NOT reduce or increase tyre pressure."
« Last Edit: May 15, 2019, 10:08:32 AM by RetroZ »

Offline Travelman

  • Z900RS Member
  • **
  • Posts: 18
  • Bike: Z900RS / FJR1300
  • Town / City: South Shields
  • Country: gb
Re: Tire Pressure
« Reply #42 on: May 15, 2019, 10:45:18 AM »
Thatís an interesting link RetroZ. Iím rethinking my position, though Iím still unsure about this idea of universal pressures.

Edit: Incidentally I see that the article is nearly 20 years old so there may be newer research.
« Last Edit: May 15, 2019, 10:47:35 AM by Travelman »

Offline Evangelos K

  • Z900RS Member
  • **
  • Posts: 17
  • Bike: 2019 Z900RS cafe
  • Town / City: New Orleans METRO
  • Country: us
Re: Tire Pressure
« Reply #43 on: May 15, 2019, 01:03:10 PM »
Well, the idea of ďtyres designed to be operated at a standard 36 & 42psi, in all conditionsĒ is in itself a contradiction.  Unless ďmagic rubberĒ has been invented.  By definition, a tire responds to load.  A 1000LBS cruiser and a 40LBS sport bike will not make the tire operate the same in any condition.  Add to that cruiser 2 riders and cargo, over 1400LBS.  And make the sportbike a 300CC at 340LBS...

The issue is higher pressure is better than under inflation, so the recommended pressures are on the safe side.  But really, nothing in the 30íís range is under inflation. 

Donít do as I say... thatís what I do, and anyone can disagree. For me, 32/36, and 32/34 on my bikes works and handles better; tangibly better, on the road. You canít tell me at the track, where you will see high temps nowhere near, ever, you will get on the road, Iím in danger running 31 rear, 34 front HOT.  That is on ďproduction tiresĒ btw.  They donít crack, shred, etc...and the wear patter is perfect.  If the tyres were designed to be operated at a standard 36 & 42psi, in all conditions, well, tracking them is all conditions, right?
2018 Triumph Tiger XRx
2013 Triumph Street Triple R

Offline Forks-by-Matt

  • Approved Vendor
  • Z900RS Pro
  • *
  • Posts: 174
  • Town / City: Alexandria, VA
  • Country: us
Re: Tire Pressure
« Reply #44 on: May 15, 2019, 01:19:44 PM »
*Originally Posted by RetroZ [+]
Then, all the motorcycle tyre manufacturers agreed to build tyres designed to be operated at a standard 36 & 42psi
No, their LAWYERS did. If there was the slimmest of engineering input it was that yes, we'll design the casing to run at a MAX cold PRESSURE of 36/42 at STP.

We, GoodYear,
make shitty-ass CAR tires.

what the evidendce always confirms is that running tyres outside of the recommended pressure, is dangerous

Say you set pressure and it's 50F ambient. Your tires are an easy 10% out of spec at 75-80F let alone hotter. Ditto the converse. Where are all the dead bodies and smoking craters?

for motorcycles, the rider should ensure tyres are set to the recommended pressure (36/42psi)
Again MAX "do not exceed" pressure.

The article is complete and total rubbish.
Sure, if you run a tire at 25psi (25-30% deviation)  then you're adding undue stress. But you'd have to be a dunce not to notice the change in handling. Ok ok, if you have a 800lb bike with 3-400lbs of rider on it and decide you'll run "sportbike" pressures like 33/33 then yeah the tire will probably have a bad day if run long and hard.

Any standard bike in the 400lb class can safely run tires at 30-36F and 30-42R all day long on street and track. If you want to blindly obey your we-know-betters and go with 36/42, fine. But you really should do the experiment yourself and try 33-34F 33-36R and compare and contrast. I have every confidence you'll much prefer the latter.

Offline Richard

  • Z900RS Member
  • **
  • Posts: 59
  • Bike: Panigale v4s, z900rs
  • Town / City: South Bucks
  • Country: gb
Re: Tire Pressure
« Reply #45 on: May 15, 2019, 01:49:04 PM »
 :0461:
42 on the rear cold is just daft IMHO, even with 'only' c115bhp
Check pressures cold.  Go for a normal ride. Check pressures again. +4 degrees on rear is normal on street. So, if you set at 42 on rear, it was measured in your garage but it was a baker outside and you gave it the berries, your street pressure could easily be +6 degrees, so 48 psi.  So try  it and measure.   

Offline Forks-by-Matt

  • Approved Vendor
  • Z900RS Pro
  • *
  • Posts: 174
  • Town / City: Alexandria, VA
  • Country: us
Re: Tire Pressure
« Reply #46 on: May 15, 2019, 02:17:53 PM »
*Originally Posted by Evangelos K [+]
If the tyres were designed to be operated at a standard 36 & 42psi, in all conditions, well, tracking them is all conditions, right?
Indeed. Continental ran that jive past RoadRacing World during a tire test at a track and the editors mocked them in print. They ran the tires that way and wrote mean things about the resulting experience. Then they threw all caution to the wind and ran pressures more or less common for advanced riders at that track, and lo' and behold the tire performed vastly better. Who could have know'd.