Archive for April, 2011

Pirelli F1 “Soft” Tyres.

The Pirelli tyres in their second F1 in Malaysia performed well in 37 degree heat, but it adds interest to know whether they are using the “soft’ tyres or the “hard” tyres. The Yellow PZERO markings are supplemented by a gold band running around the shoulder circumference of the tyre, when the “soft” tyres are in use. These are claimed to give a reduction in lap time of around 1.2 seconds a lap for around 8-10 laps , so they do make a difference, and allow more passing manoevres.

These markings will be used in China too, but will change again for the European season, commencing May in Turkey.


April 14, 2011 at 1:34 am 4 comments


I had an expensive lesson on the destructive effects of ozone on rubber recently.
Ozone occurs naturally in the air, commonly after electrical storms, of which we’ve had a few lately.

But in this case, the destruction originated from an electric motor, immediately under the rubber seal that was supposed to keep the water in my pool’s heating system. What’s that got to do with tyres? Well, when tyres are stored, like on your caravan or on a seasonal piece of farming equipment, care should be taken to protect them from sunlight, and electric motors.

Otherwise, ozone from electric motors will attack the rubber, BUT ONLY WHERE IT IS STRETCHED!
Wide lacy cracks appear, and grow very quickly, as shown in the photo. The victim is shown in the front of the first photo, a new seal in the background. This appearance is typical.

So the temperature sensor was ejected, a geyser of salty water covered everything for 3 metres around, the pumps eventually ran dry, and an expensive repair bill resulted. All this for a 50 cent rubber grommet in the wrong place.

When removed from the pipe, the side of the seal inside the pipe was in A1 condition. This is shown in the second photo- it’s been turned over. There’s no ozone in the water, then- only chlorine.

Another place where this type of cracking occurs is in the bent rubber hoses in your washing machine. That can do a lot of damage too, replacing tiles, carpet, timber, coreboard cupboards, and maybe carpets too.

April 14, 2011 at 12:59 am Leave a comment

Caught Speeding- Blame your tyres!

It took a change of government in N.S.W. apparently, to inject some commonsense into the setting of limits for “overs” on fixed and mobile speed cameras.

The Roads and Traffic Authority had decreed that henceforth the limit would be 2%. The first act of the Minister-Elect was to decree that this wouldn’t happen. The police weighed in with the comment that a thick speedo needle, or fitting a new set of tyres, could cause an error bigger than 2%. You know what- the police were right! Incidentally, in Victoria it’s 2% for fixed cameras, and 3% for mobile cameras. What the basis is for this difference is unknown.

But both police forces admit that there is a “discretionary factor”. This was once explained to me as “the cost of the paperwork and time may make it not worthwhile for them to issue a ticket”.

The reasons for having a tolerance at all are explained in my blog article of September 2007. If the Roads and Traffic Authority staff had read this, they could have saved themselves a lot of embarrassment, and the newspapers a lot of column inches.

One thing though- you can’t change the rolling circumference of a steel-belted radial tyre by varying the tyre pressure (within normal tolerances of course). The steel belts prevent the tyre from expanding. That’s what they are for.

April 14, 2011 at 12:54 am Leave a comment