Tyre pressure, have you checked yours lately?

[Samurai]

My boss is leaving for India today, I asked him to pick this Inflator from Sears.

I'll have it by next week.

[Shan2nu]

My boss is leaving for India today, I asked him to pick this Inflator from Sears.

Sounds pretty good. When i'd gone with Rehaan to get his car horn fixed, we too saw something similar to this but, i don't think it had an electronic cut off. The guy was asking 600 bucks for it.

Shan2nu

[Rtech]

I've had one of these protable compressors in my car for years now. Can't even count the number of times it has saved me the hassel of changing tyres in the middle of the night or in other situations. It's really a must have for everyone.

[Shan2nu]

Can't even count the number of times it has saved me the hassel of changing tyres in the middle of the night or in other situations

So, when ever you have a flat, you just use the puncture kit, blow air back into the same tyre and drive on? Hmmm, what kit do you have?

Shan2nu

[jigarmuni]

Originally Posted by Shan2nu

Which race track are you talking about? And what car was this on?

Yup, i always trust downshift to the right gear and rpm. Nothing better than that. It even makes the Wagon R look good. LOL

Tried toe-heel braking but still need a lot of practice with that.

Shan2nu

its the racing circuit at sriperumbedur (Chennai) & one more at coimbatore.... They are formula cars with maruti engines. Infact we used very low pressures over there about starting from 19 to 21 depending on the weather conditions and the balance of the car. It has taken me almost 6 months to get in terms with heel and toe braking dude... dunt ask!!! requires a lot of practice!!

[Rtech]

Originally Posted by Shan2nu

So, when ever you have a flat, you just use the puncture kit, blow air back into the same tyre and drive on? Hmmm, what kit do you have?

Shan2nu

No. Never used the puncture kit while on the road yet. I've had a couple of nails that caused a slow leak. Once was when i was on my way back from kholapur at 2 am. Not the time you want to stop and fix a flat on a dark highway. So just filled it up and continued. Fixed it the next day.

Same thing happened a few times when I got out of the house for work in the morning. Nothing worse than seeing a flat tyre first thing in the morning. So instead of getting sweaty and dirty fixing it, just fill it up and drive and get it done when you have the time.

Did I mention how much I love tubeless tyres

[Shan2nu]

Yup, tubeless is the way to go. A lot safer than the normal tyres.

Shan2nu

[Rtech]

Infact we used very low pressures over there about starting from 19 to 21 depending on the weather conditions and the balance of the car.

Jigar, a FISSME car is a rear engined, rear drive, single seater weighing less than 500Kg. The tyre pressure would have to be reduced significantly as compared to a regular M800. Also, racing and road driving are two completely different things. On teh track you are always going flat out, hence the tyres heat up and stay hot for most of the session.

On the street, you rarely get enough heat into the tyres by simply driving in the city at normal speeds with the occasional blast.

[jigarmuni]

Originally Posted by Rtech

On teh track you are always going flat out, hence the tyres heat up and stay hot for most of the session.

On the street, you rarely get enough heat into the tyres by simply driving in the city at normal speeds with the occasional blast.

so, thats the whole idea here!! we started the topic with reducing tire pressures when driving on the expressway!!! with a few ppl. thinking otherwise! On the track we are doing average speeds of 100kph.... on the expressway its an average of 160kph! OS surely the tires to tend to heat up quite a bit...... hence the need for reducing tire pressures!!

[RX135]

Originally Posted by jigarmuni

On the track we are doing average speeds of 100kph.... on the expressway its an average of 160kph! OS surely the tires to tend to heat up quite a bit...... hence the need for reducing tire pressures!!

Reducing tyre pressure for higher speeds? Did I get you correctly? Tyres do not get burst because of over pressure, but because of flex in sidewalls. I think, this has already been discussed in earlier posts. See some weblinks posted earlier.

[speedsatya]

Originally Posted by RX135

Reducing tyre pressure for higher speeds? Did I get you correctly? Tyres do not get burst because of over pressure, but because of flex in sidewalls. I think, this has already been discussed in earlier posts. See some weblinks posted earlier.

yeah ,
RX is right.dont even think of doing so.if u have reduced ur tire pressure when on the expressway,then you are too lucky.actually it is usually recommended that u increase the pressure by 3-4psi atleast .
and according to simex tire.com

Originally Posted by www.simextire.com

The Minimum Compliance Plate Pressure, usually located on the door sills of the front doors or in the fuel filler flap, has been devised by your vehicle manufacturer as a guide to running the correct tyre pressure. This minimum pressure is designed for a vehicle consistently running at 80km/h or less unloaded (ie two persons in the vehicle). This is the correct pressure to be running for general daily driving.


Loaded Vehicle

A loaded vehicle is defined as having the weight of up to 4 persons plus shopping and baggage. If you regularly drive in the city with these loads, use the following to calculate your recommended tyre pressures.

Minimum Compliance Plate Pressure +28 KPA (4 PSI) --- both front and rear.


Speed

If you are constantly driving at high speed (ie 100-120 km/h for over 1 hour), then you should use the following to calculate your recommended pressures.

Minimum Compliance Plate Pressure +28 KPA (4 PSI) --- both front and rear.


Speed & Load

Considering the increased pressures for both load and speed scenarios, for driving at speed with a load, you should use the following:

Speed Pressure Increase + Load Pressure Increase + MCPP = Minimum Compliance Plate Pressure +56 KPA (8 PSI) --- both front and rear.


High-Speed

High speed is defined as driving at 120km/h for over one hour. When driving at high speed regularly, use the following calculation:

Speed Pressure Increase + High Speed Pressure Increase + MCPP = Minimum Compliance Plate Pressure +56 KPA (8 PSI) --- both front and rear.

[Rtech]

Tyre pressure adjustments on a race car are done taking into account the compound of that tyre, the ciruit it is running on, the type of car you are driving and how you want to set it up. The sole purpose is to get a quick lap time and make the tyre last the entire race.

What I'm saying here is, what works on the track will not always work on the streets.

I had a similar mindset to what Jigar has now. Take a look at my first few posts in this thread to see that. These things were built into my thought process when I was racing. While it does hold true in races e.g. you expect the pressure to rise due to the rising heat the more laps you do, hence you keep that in mind when setting up the car.

But, while race compound tyres are quick to heat up (at those speeds), they also have a very narrow window in which they operate best. That's why a race compound tyre on the streets will always be inferior in all levels of performance as compared to a sporty street tyre. The street tyre is designed keeping in mind the low speeds and spot/start nature of driving. These tyres are designed to operate within a much larger temperature window on a variety of surfaces and weather conditions.

You may think that the 45 mins you spend driving on the expressway at an average speed of maybe 100kmph (160 average is practically not feasable!) would be enough to heat up the tyres to the extent that the pressures would rise enough to cause a blow-out, hence logically you should run lower pressures to negate that rise.

The reality is that at these slower speeds, running with a lower pressure, consequently more sidewall flex, would infact create more heat in the tyre than it would if you were running the recommended pressure or even 1-2 psi more. Basically it is a matter of choosing the lesser of the two evils.

There is no fixed formula and it varies depending on the tyre, its speed rating, its profile, its compound, the car you are driving and finally the driving style. Try a few variations and you will find the best pressure needed for your car on that road.

[Rtech]

There is no fixed formula

No sooner do I type that line and someone comes up with a "formula"! lol!

Well, 8 psi above! Not for me thank you! I'll stick to my seat of the pants formula.

[Samurai]

Originally Posted by Shan2nu

Sounds pretty good. When i'd gone with Rehaan to get his car horn fixed, we too saw something similar to this but, i don't think it had an electronic cut off. The guy was asking 600 bucks for it.

Shan2nu

Except my Santro doesn't have 12V power outlet. I know Baleno has, does Petra have a 12V power outlet? Is there a way I can add 12V outlet to a Santro so that I can use this Inflator?

[speedsatya]

Originally Posted by Samurai

Except my Santro doesn't have 12V power outlet. I know Baleno has, does Petra have a 12V power outlet? Is there a way I can add 12V outlet to a Santro so that I can use this Inflator?

hey samurai,
there should be a provision for a 12v outlet like a cigi lighter or mobile charger.
i think,any electrician should be able to do it for u.


or else ,if you dont want any cutting of wires to be done,tell your boss to get a foot pump for you.i have it and it really helps.