Jump to content

A More Complex Than Usual Tyre Pressure Question


Recommended Posts

I recently attended a Level 3 school.

 

When lined up for scrutineering a couple of techs came down the waiting lines and adjusted tyre pressures on every bike. I noticed he was spending some time on my rear and asked what pressure he was setting. He replied "we're setting all bikes to 30 lb front and rear." I expressed concern with this because that's 12 lb below recommended for my landbarge Suzuki Bandit. The tech looked sheepish and replied "it'll give you a bit more grip"

 

Ambient temperatures were expected to be high - it was 25degC (75F) at scrutineering and peaked at 38C (100F) that afternoon.

 

I'd never seen this practice at any other school or trackday before.

 

During the first two sessions I had hot tearing on the rear (the rubber scrubbing off the tyre formed diagonal ridges from 1/3 down the shoulder of the tyre to almost the edge). It settled to more normal balling pattern as ambient temperatures rose but was still shedding a lot more rubber than at the pressures I normally run at trackdays.

 

I'm actually more interested in the human factors in the response of myself and other riders to an unexpected situation and the way we responded but just wanted to get any opinions on the technical side first.

 

So - any thoughts welcomed.

Link to comment
Share on other sites

I'm not sure if you attended a school in the U.S.; I can only speak to how we do it here, but here's the scoop:

We DO check tire pressure on every bike, every day. It's a safety issue and part of our tech process.

Tire pressures are set based on type and brand of tire - we do NOT set all tires the same. For example, many race tires are designed to run low pressure in the rear, around 21-23 psi.

At tech we have and use a reference card which his a list of tires by type and brand with recommended cold pressure for track. If we run across a model or brand we don't have specifically listed, we go by type (street tire, street/track tire, race tire) and/or ask our mechanic for a recommendation.

School bikes on Dunlop Q3s are set normally to 31 psi front, 30 psi rear. This is sometimes changed by the mechanic on the day of a school if there is something more appropriate for a certain track or expected temperatures.

If a student requests a particular pressure and is knowledgeable about track riding and why they want that pressure, we typically set it to the students request.

If a student has what is obviously a track-dedicated bike and/or is running tire warmers, we usually ask if they have a preferred pressure.

 

It is VERY VERY common for students to arrive with their own bike with tires pressures set way too high for track use. Motorcycle shops and dealerships set the tire pressure to what is recommended for street use, which is a generic pressure set to handle a lot of weight, possibly including a passenger and luggage. For example, we often see pressure of 45-50 psi for a tire that should be run at about 30psi for the racetrack.

 

Most manufacturers of tires designed for street AND track will have different recommended pressure for street vs track use, BUT that can be hard to find - in many cases it is only provided to tire distributors that service track days.

 

Since it is so common for students to show up with a street bike with very high pressures, it is easy to fall in the habit - when you see a street bike - to simply lower the pressure according to what is recommended for track without asking what the rider prefers; if you DO ask, most riders will look and feel a little panicky, since they don't know the answer. In your case, since you asked about it, the tech person should have provided a better explanation (it does provide more grip, so at least he/she made an attempt to explain) but if you were not happy with the pressure recommended, the tech person should have either used the pressure you requested (if reasonable) or sent you to the mechanic to provide an expert recommendation and work with you to come to a decision you were comfortable with.

 

The number one priority is safety, always, but the number two priority is to make sure that the tires are not a problem or a distraction for you; in this case it seems you had concerns, and that should have been addressed.

 

You are ALWAYS welcome, at a school, to show the mechanic your tires and ask questions about the wear, the pressures, etc.

Link to comment
Share on other sites

Hotfoot, thanks for a very comprehensive answer. (and the school was in Australia)

 

I queried the pressures twice - once while being set and again after the first session when I was getting hot tearing. I let it go when temperatures rose and it began to move back towards a more normal balling pattern (I assume with the temperature rise pressures rose enough to better stabilise the carcass.) For background I usually drop pressures no further than where the "orange peel/sand dune" tyre surface is lost. 36lb seems to be about the lowest I can go on my Bandit. I should have asked what they would have set on my other bike - a KTM 690 Duke (which has recommended of 29lb) to understand the policy better.

 

The officials were getting many queries from many riders and they appeared unsure in their answers. I'm guessing this was the first or one of the first times the policy was put in place. I'd never before seen CSS staff unsure about anything. At schools and trackdays they've always been a well oiled machine.

 

I imagine the policy will be reviewed - I struggle to understand how 600 sport bikes, a BMW K1300, a Kawasaki 1400GTR (Concours 14) and my landbarge could be expected to be optimised at the same pressure.

 

But as I said in the OP I was more concerned about my reaction to the situation (yes, I was concerned and distracted) and that I accepted the situation without pursuing clarification.

 

And there you go, you often learn more at a CSS class than just technique.

 

As an aside, I still struggle a bit calling the school CSS. When I started it was called Australian Superbike School here. If you're talking to Keith anytime soon could you ask him if Steve Brouggy can call it that again? I used to love telling people I was going to ASS School :P

Link to comment
Share on other sites

Road pressures are too high for track use. I even use very close to track pressures on the street for my bikes.

 

Think of it this way. What's worth more to you? A little bit of extra tire life or more traction that might prevent an accident that could injure you and destroy the bike. Tires are disposable people and bikes not so much. :)

 

The school is super flexible on pressures if they are comfortable with your reasoning. I ran tire warmers this year on my bike and requested that they set the pressure "super high" so that I could bleed out air to set the hot pressure. They did ask what hot pressure I planned on using and gave me some advice based on track conditions which was super helpful.

 

So... I was wondering... Any chance of that tire pressure card getting released as a PDF with the school's logo on it? Might be quite useful for helping the school with advertising and for people like myself who deal with a lot of never been on the track Novice riders helping them get a "safe" track pressure. I would be glad to help out with getting the card presentable. I do however understand if the answer is no. Legal liability and the effort put into research and such.

Link to comment
Share on other sites

Road pressures are too high for track use. I even use very close to track pressures on the street for my bikes.

 

Think of it this way. What's worth more to you? A little bit of extra tire life or more traction that might prevent an accident that could injure you and destroy the bike. Tires are disposable people and bikes not so much. :)

 

The school is super flexible on pressures if they are comfortable with your reasoning.

 

I certainly agree with your first point and note that they are two completely different environments. I usually alter my road pressures as a best guess of the conditions and type of riding expected that day.

 

For me, tyre life was never a consideration, only that I thought that that the tyre was overheating and therefore losing grip and stability. (I hadn't mentioned this before - the rear was a Michelin Pilot Sport 3. I had a Q3 fitted to the front at the track and it fared much better)

 

Previously over here plenty of advice was given but the choice was left to the riders. This was the first time I'd seen a blanket rule imposed and hence the reason for the post.

Link to comment
Share on other sites

Without seeing the tire it's difficult to say what going on with it. We have resident tire reading experts on the forum that would be glad "read" the tire wear if you post a photo.

 

When it comes to tire pressure it's often better to error on the side of lower pressure than higher pressure. The tire wear that you often see can be concerning but in most cases there's no loss of grip unless the tire is starting to turn blue or get greasy. The blue color and the greasiness is the tire overheating and releasing the oils that make it resilient. If you see bluing or a greasy tire talk to your tire guy ASAP.

 

It's always a trade off of course. Lower pressure there's the risk of overheating and excessive sidewall deformation but higher pressure there's a smaller contact patch and the tires don't heat up as much. Seeing and feeling the issues with lower pressure is more predictable than higher pressures where there's just a sudden loss of grip. It's also important to keep in mind that as a tire heats up it "grows" in pressure. The school sets a base line pressure that you set and forget for the whole day. When I take my bike to the track I set a hot pressure and adjust it every session and have to keep the bike on warmers. It's a different approach that allows the student to focus on the learning rather than their tires. In fact this is an object lesson I learned this year myself at the school. Running back and forth from the classroom to the track it was a huge effort to put my bike on warmers every session on a school day schedule. It got even more complicated with some rain showers and electrical cords. It's not so bad on a track day where you have a lot more time.

 

Q3's are an amazing tire. I had a set on my BMW and got an entire season of track riding on the set. I eventually switched to another brand of tires but I do miss the amazing longevity that the Q3's offered. Interestingly enough with the advice of a more experienced rider I dropped the pressure on my Q3's below 30 PSI and got some pretty amazing grip without overheating them or wearing them out prematurely.

Link to comment
Share on other sites

Tag, it is reasonable to me that your heavier bike may need to run a higher pressure than the lighter weight sport bikes. Since you are knowledgeable about what pressures work for your bike, it would have been better to set the pressures to what you requested so that it was not a distraction.

Your feedback has sparked some discussion between the U.S. branch and the Australia branch, the policies are being reviewed. Thanks for the specific and constructive feedback, the information is being put to good use. :)

Link to comment
Share on other sites

Ok, so I've learned two things.

 

One:

When something concerns me that is a safety issue I should put the effort in with the school staff to understand the problem fully. Due to the depth of knowledge and professionalism that CSS staff have always displayed when I've been there I found it hard to really push the issue, thinking it was me that was more likely to have the wrong reasoning.

 

Two:

This place rocks. It's like having the school in my computer. Why did I lurk for so long :ph34r:

 

Also, I kicked myself for not bringing it up during the theory sessions and particularly at the afternoons wrapup when Steve Brouggy stood at the front of the room and said in a very clear voice "Ok any questions about today or anything about motorcycling in general?" We all sat there like stunned mullets, of course, with me straining to think what it was that I should have been asking. I had the forehead slap moment half way home ------ "DOH, THE TYRES!!!"

 

But the forum here has certainly worked for me, to help out after you've left the track.

 

Thanks for all replies.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...