Tire Pressure

[raro]

checked the tire pressure for the first time after buying my new car. The sticker at the driver door says 30 psi on all 4 wheels, but it was set to 42 psi an all four wheels. 50 psi being the maximum pressure according to what is written on the tires.

I noticed that before when changing tires that they pump them up like crazy...I understood this was just being careless but all four set to the same high pressure by the car dealer that made otherwise a very professional impression?

They are 215/45/R17 tires. What are the recommendations/implications? As to my understanding higher pressure makes the tires last longer but the pay-off is less grip....right?

[Gary A]

Thais routinely over inflate tires because that makes them roll easier. Rolling easier gives better fuel economy or so they believe.

[Mrjlh]

Over inflation of tires is not recommended for two reasons. First your tires will wear out faster. and secondly, it reduces the road grip the tires has been design for, hence you lose traction in turns and during stops. The so called increase in gas mileage is actually nil by years end. Plus you'll need new tires sooner. The only time over inflation is really required is in cold temperatures where normal air pressure is reduce. It's about one PSI per every ten degress Fahrenheit starting around 70 degrees downward. As you drive your tires heat up especially here! You can easily destroy your tires faster.

Most tires are under-inflated anyway. An over inflation of only 2 PSI over the recommended rating is common because most gauges are not accurate at gas stations. They are accurate to 1-2% value depending on the quality of the gauge. They get abused so buy an accurate gauge and carry it in the car.

[Tywais]

The sticker on the door of my new Civic 2.0 states 33 front and 32 rear. First thing I checked after driving it home from the dealership and waiting a few hours due to reports here. Checked them and they were 33 front and 32 rear. Also, they should be checked/inflated to spec when cold.

More info here

//edit - I was surprised that they put on performance and good quality tires Michelin Preceda. Unfortunately that means replacements run nearly 8,000 Baht per tire.

[Spoonman]

I generally run my tyres 2psi higher than factory specs, dont really know why, force of habit from fitting tyres for many years i guess.

Edited November 14, 2009 by Spoonman

[culicine]

The sticker on the door of my new Civic 2.0 states 33 front and 32 rear. First thing I checked after driving it home from the dealership and waiting a few hours due to reports here. Checked them and they were 33 front and 32 rear. Also, they should be checked/inflated to spec when cold.

More info here

//edit - I was surprised that they put on performance and good quality tires Michelin Preceda. Unfortunately that means replacements run nearly 8,000 Baht per tire.

The michelin pilot precedas should be about 5K a tyre. I got them 2 years ago for 4600 each. That was 215 / 45 / 17. These are great tires - I could have gotten over 50K kms out of them , but the rears got unevenly worn for some reason and then really noisy. If you can keep the wear even you should easily get 60K kms from them.

[Tywais]

The michelin pilot precedas should be about 5K a tyre. I got them 2 years ago for 4600 each. That was 215 / 45 / 17. These are great tires - I could have gotten over 50K kms out of them , but the rears got unevenly worn for some reason and then really noisy. If you can keep the wear even you should easily get 60K kms from them.

Thanks for that info. I just looked at one site out of curiosity and they were quoting around 7800 Baht. 4600 is still high but certainly more acceptable. With my driving distances 50kms will be about the time I finish paying the car off.

[Stumbo]

Interesting. My girlfriend has a Yamaha Nouveau which has been a really comfortable bike to ride. However she got the tires checked at the local shop, and now it is a spine cracker over bumps and very unconfortable. I suspected that idiot overinflated, now I will check. Thanks.

[torrenova]

They all over inflate tyres. The concept that these companies spend billions on getting things right is lost on Somchai and his mates who "know" more than Bridgestone for example.

[soundman]

Another factor in tyre performance versus inflation is the actual load being supported.

A Van is a good example. You may use 32 - 35 PSI for regular driving around, however, you will need to run the pressure up to around 40 - 45 PSI when you have a heavy load for the same tyre performance.

[sibeymai]

Just recently got 75,000ks (could have got another 5k) out of the original Goodyear NCT5s on the wife's Jazz. With mileage like that I had the same put back on. Hope they wear just as well.

Another effect of running too high PSI is that the steering will wander all over the place making driving long distances or at high speed a chore and somewhat dangerousif you don't pay attention. Brakes also lock up sooner or reach their grip threshold quicker. Not a huge problem in the dry but on a wet road it can greatly increase the stopping distance.

[nam-thip]

I refuse to let a Thai inflate my tyre’s as they inflate to the point of solid.

They simply don’t understand about tyre pressures and the importance of them being correct.

Incorrect tyre pressures affects steering and one of the checks carried out either at the scene of an accident or at roadside spot checks in the UK is your vehicles tyre pressures which according to the experts can be a deciding factor in the event of an accident.

An example of Thai’s inflating a tyre to the point of ‘solid’ is that i recently checked the tyre pressures on my wife’s step-through motorbike after she had them inflated at the local Thai repair shop and the front had 47psi whilst the rear had 58psi with not a pressure gauge in sight she informed me.

[raro]

Another factor in tyre performance versus inflation is the actual load being supported.

A Van is a good example. You may use 32 - 35 PSI for regular driving around, however, you will need to run the pressure up to around 40 - 45 PSI when you have a heavy load for the same tyre performance.

so we can conclude that the over-inflation results from permanent overloading? Suddenly it all makes sense...

[raro]

still bit confused/worried. The front tires look like there is not enough air in there. Checked with cold tires at the gas station, 30 psi as per Honda's recommendation.

Now...could it be that different tire makes require different pressure ratings despite same tire size?

[powderpuff]

Real simple. ask the dealer why.

[katabeachbum]

still bit confused/worried. The front tires look like there is not enough air in there. Checked with cold tires at the gas station, 30 psi as per Honda's recommendation.

Now...could it be that different tire makes require different pressure ratings despite same tire size?

Tyre pressure is calculated by the car maker for specific size of tyre +/- a few%. Then its tested for a couple of years and a few million km if the calculation is correct on this model, before presenting it in the showrooms.

Correct tyre pressure does not change with make of tyre, but may change some if a very different size is being used.

Recommended tyre pressure performs best (traction, steering and braking) and gives optimal lifetime.

Pressure meters at gas station are often incorrect, and your tyres are usually to hot when arriving gas sation. A small meter can be purchased at 120-200 baht, and pressure can be checked before tyres are heated by sunshine and friction during driving.

New vehicles usually leave manufactorer with storage pressure, often 45 psi, to avoid squared tyres before vehicle is delivered to customer. This is supposed to be adjusted to correct driving pressure on predelivery service. I have taken delivery on 9 new cars/trucks in LOS, and they have always been still on storage pressure

If vehicle is parked for more than a month, storage pressure is recommended. Tyres max allowed storage-pressure can be read on the tyre.

[raro]

interesting, this storage pressure! That was the pressure the tires had when I bought the car.

Never check the pressure when tires are hot, the next gas station with decent pressure checkin is no 500 m form the office...should be ok.

[katabeachbum]

interesting, this storage pressure! That was the pressure the tires had when I bought the car.

Never check the pressure when tires are hot, the next gas station with decent pressure checkin is no 500 m form the office...should be ok.

Every time I have serviced a car I check the pressure and its usually to high but not as high as storagepressure. I have tryed to show them the pressure recomondation sticker, but they still overinflate. Just use my own meter and deflate to correct pressure.

My previous Vigo 4X4 2006 has now 70k km on it and is still running original 16" Michelin with good tread due to correct pressure. New owner wants to replace them ahead of next rainseason, probably with 90k km on them, due to age not lack of tread.

Sparewheel should be kept with storage pressure, and then be deflated if need to use.

[torrenova]

still bit confused/worried. The front tires look like there is not enough air in there. Checked with cold tires at the gas station, 30 psi as per Honda's recommendation.

Now...could it be that different tire makes require different pressure ratings despite same tire size?

I really thought the same as you for my D-Max and was "certain" that the bulging front wheels were due to too low tyre pressure. I ran them at about 34 and then put them down to 31/32 and at 31 (calibrated on my measure not the garage), the ride is much better in the dry and far far better in the wet. The vehicle just hugs the road much more and the whole ride is better. I have overcome my beliefs and just go with the manufacturers superior knowledge on this point.

[MikeyIdea]

It is actually not a bad idea to go above recommended pressure with 10 to 15% when you are driving long distances or have heavy load. Reason is that long distance at motorway speeds heat up tires considerably, so does heavy load and what most people don't know - tires running at higher temperatures than they are designed for wear out much faster than if they were operating within design temperature. Going above recommended pressure while driving in Bangkok will certainly wear out tires faster, doing it when driving to Phuket in Thailand daytime will help tire wear actually - Unless it's raining more than half the way

Edited December 8, 2009 by MikeyIdea

[aitch52]

Just got my car back from service from the dealer, checked pressures same day. Offside front 42 psi, nearside front 36 psi, offside rear 32 psi, nearside rear 36 psi. Target pressure 29 psi all round, doh.

[katabeachbum]

Just got my car back from service from the dealer, checked pressures same day. Offside front 42 psi, nearside front 36 psi, offside rear 32 psi, nearside rear 36 psi. Target pressure 29 psi all round, doh.

thats service in paradise

should check your sparewheel too, recomend 45 psi to be deflated if needed

[katabeachbum]

It is actually not a bad idea to go above recommended pressure with 10 to 15% when you are driving long distances or have heavy load. Reason is that long distance at motorway speeds heat up tires considerably, so does heavy load and what most people don't know - tires running at higher temperatures than they are designed for wear out much faster than if they were operating within design temperature. Going above recommended pressure while driving in Bangkok will certainly wear out tires faster, doing it when driving to Phuket in Thailand daytime will help tire wear actually - Unless it's raining more than half the way

disagree

my 2008 Accord 2,4 has been running recommended pressure for 75k km, with at least 60k km on highway normally cruising 140-160kmh between Hua Hin and Phuket. still on original Michelin Pilot 225/50-17 with even treadwear, and no need to replace yet.

[MikeyIdea]

You don't write the most important piece of information, and I didn't mention it either - the speed rating. I bet you have V tires. You are not going above design temperature on 50 profile V tires at 140 to 160 km/h. V tires are rated for up to 240 km/h, H tires up to 210, R up to 170 etc. Some German vehicle manufacturers have 2 recommended tire pressures, one normal and one to accomodate for high speed driving. Top speed of the car isn't higher than the speed rating of the tires they put on of course, it's just that everything in life is a compromise. Some 25% lower than design speed is when it is recommended to increase tire pressure in Germany. Thailand is much hotter than Germany. Long distances at 150 km/h daytime in Thailand and we should increase pressure of an H tire with 10 to 15%. You are right, V tires at that speed doesn't wear out quicker

Tires running at higher temperatures than they are designed for wear out much faster than if they were operating within design temperature

[katabeachbum]

You don't write the most important piece of information, and I didn't mention it either - the speed rating. I bet you have V tires. You are not going above design temperature on 50 profile V tires at 140 to 160 km/h. V tires are rated for up to 240 km/h, H tires up to 210, R up to 170 etc. Some German vehicle manufacturers have 2 recommended tire pressures, one normal and one to accomodate for high speed driving. Top speed of the car isn't higher than the speed rating of the tires they put on of course, it's just that everything in life is a compromise. Some 25% lower than design speed is when it is recommended to increase tire pressure in Germany. Thailand is much hotter than Germany. Long distances at 150 km/h daytime in Thailand and we should increase pressure of an H tire with 10 to 15%. You are right, V tires at that speed doesn't wear out quicker

Tires running at higher temperatures than they are designed for wear out much faster than if they were operating within design temperature

My 2006 Vigo has 16" S tyres (180 kmh) and has done the same distance approx 40k km, by now covered 70k km, still on original Michelin Cross road with even tread. Highway cruisingspeed is the same 140-160kmh. Since the tyres are rated 180 kmh at 25C, I consider 160 kmh topspeed for this vehicle to be on the safe side.

With all the German cars I had back home (mostly VW, Audi, BMW, Benz), I v never seen anyone recomend increased pressure for driving less than 160kmh

Edited December 14, 2009 by katabeachbum

[Bung]

Can't recommend enough to buy a good tyre pressure gauge and leave it in your car. Check the pressures yourself about every 1-2 months and before every long trip and teach your wife how to do it if she drives the car.

Worthwhile checking the manufacureres website if you change brands to see what their recommended inflation is and put extra in the back if carrying a heavy laod. Use your common sense and don't go over the max pressure.

I got 90k out of the Duellers on my 4x4 vigo and ran them at 29 - 31.

I put Michelin cross terrains on and they seem happier at 32/3 max is 35.

[katabeachbum]

Can't recommend enough to buy a good tyre pressure gauge and leave it in your car. Check the pressures yourself about every 1-2 months and before every long trip and teach your wife how to do it if she drives the car.

Worthwhile checking the manufacureres website if you change brands to see what their recommended inflation is and put extra in the back if carrying a heavy laod. Use your common sense and don't go over the max pressure.

I got 90k out of the Duellers on my 4x4 vigo and ran them at 29 - 31.

I put Michelin cross terrains on and they seem happier at 32/3 max is 35.

If you run Michelin Cross Terrain at 29-29 (31 heavy loaded) they will return same 90k km lifetime.

[MikeyIdea]

Katabeachbum, you didn't live in a country where they have free speed on the motorways, no need

Everything in life is a compromise, every design is a compromise. You cannot design to suit all scenarios, there is nothing strange in increasing tire pressure a bit when pushing tires to make them stay within design temperature.

With H tires in Thailand, I recommend increasing pressure 10% when driving long distance at 150-160 km/h or over.

Edited December 15, 2009 by MikeyIdea

[katabeachbum]

Katabeachbum, you didn't live in a country where they have free speed on the motorways, no need

Everything in life is a compromise, every design is a compromise. You cannot design to suit all scenarios, there is nothing strange in increasing tire pressure a bit when pushing tires to make them stay within design temperature.

With H tires in Thailand, I recommend increasing pressure 10% when driving long distance at 150-160 km/h or over.

Autobahn to Switserland or Brennerpass several times a year. Never liked to cruise faster than 200kmh though.

Used to work for a high end car manufactorer, and I know how many years and millions of km have been done to find correct tyre pressure (among other things).

In principal I agree higher pressure is needed when extreme conditions, but I dont see average TV driver adjust pressure for a 10 hours ride BKK-Phuket, and then adjust it again when arriving Phuket to have correct pressure while in Phuket. 10 years back I used to do, but I v become lazy and modern tyres 45 profile and up seems less sensitive on pressure. Door sticker pressure seems to work fine in all driving conditions.

But then again, I dont like to push the tyres. S=180kmh is 160 limit for me. V=240 is 210 limit for me. After all, these classifications are with airtemp 25C

[MikeyIdea]

I admit that I am getting lazier and lazier as the years go by, I increase pressure before leavling Bangkok and don't bother to reduce it when I get back from Phuket now-a-days

Tires seem to loose pressure faster in Thailand than in northern Europe, petrol station gauges are so inaccurate that not even God knows what the real pressure is... Mai pen rai la...