tyres inflate

[tali122]

how often should front tyres (fwd) car be reinflated- i overinflate and still have to pump them up reguarly in less than 2 weeks , i dont do much mileage and dont carry any particuarly heavy loads

however it is def not a slow puncture

[stanleyman]

The pressure can vary according to the tyre temperature such as the sun on them and driving so you should check them when they are cold with the same tyre gauge to avoid any variations. Make sure the valves are not leaking and you use dust caps. If the tyres etc. are in perfect condition then they should stay up almost indefinitely but in reality every few months will be about right but check them every month. You should not over inflate as it will cause uneven wear. If you are losing pressure regularly then there must be a leak somewhere. Get the tyre fitter to check them.

[PhilBy]

If you don't do much mileage tali122 then you have nothing to worry about, it's perfectly normal for a standing vehicle to lose tyre pressure .... it's all to do with the tyre sealing against the rim, the less use it gets then air will eventually, very slowly find a way out, but when the wheels are on the move the tyre will seal itself more firmly against the rim.

By the way, over inflating tyres is a very dangerous thing to do, apart from quicker tyre wear you are also giving the tyres less grip and by doing so you are lengthening the cars stopping distance.In an emergency, over inflated tyres will skid and that extra ground that you lose skidding could be the difference between impact or not.

Keep yourself safe tali.

I

[stanleyman]

When I did tyre fitting it was the air pressure that sealed the tyre against the rim, not the weight of the vehicle. Funny how my spare never loses pressure!

[qapmoc]

Are these good quality tyres or the cheapest of the cheap type. If they are good tyres then it might be the valves are leaking, make a mix of water/wash liquid 50/50% take the valve cap off and put a drop of liquid on the valve opening and see if it makes bubbles and put liquid around the base of the valves and check for bubbles. You don't mention the age of the car, but if it is really old the rims themselves might have corrosion stopping the tyres to seal correctly.

[PhilBy]

I'm glad to hear you say 'when you were a tyre fitter' stanleyman! When you mentioned your spare wheel I thought you had nearly grasped the obvious, but falling short of learning the laws of physics take your spare wheel, place the full weight of the front end of the car on it and check your air pressure again, even a shorter time if the tyre has done several thousand miles.

Whilst on the subject of weight where on earth did I say it was the weight of the car that kept the tyre sealed?

[PhilBy]

oops......... check again in 2 weeks

[PhilBy]

A quick google later:

Q Why do I have to check my tyre pressures?
A Rubber is naturally porous and all tyres will suffer from air loss due to
porosity leaks, bead and rim leaks (due to badly fitted tyres, rusty or damaged rims) and valve leaks. An under inflated tyre will cost you more money in extra fuel (greater rolling resistance), Extra tyre wear, uneven tyre wear and are positively dangerous.

[stanleyman]

I don't understand what you are talking about PhilBy and I don't think you do either. It is not normal for a tyre to lose pressure just by standing for a few weeks and I've worked with vehicles of all sorts for many years. All my vehicles and seven or eight trailers would have flat tyres by now. I haven't had to put air in my caravan tyres for nearly two years since it was new, it stands a long time!

The pressure on the rim is still the same, how can it alter just by being still? You said when it is moving the tyre will seal itself more firmly against the rim, if it is not the vehicle weight that does it then what is it, centrifugal force? The tyre goes down quickly, simply because it has a leak in the tyre, valve or wheel. I think it is you who needs to learn physics.

[tali122]

thanks for info .i will add that it has only occured on 2 french (citroen ax , peugeot 405)cars that i have owned. uk and japanese no probs

[PhilBy]

http://www.tirerack.com/tires/tiretech/techpage.jsp?tech id=74

[stanleyman]

Thanks PhilBy, that link just confirms what I said in the first place!

[PhilBy]

And your comments on the fact that on average a tyre will lose about 1psi a week is??????

[stanleyman]

PhilBy, I think you need to put your reading glasses on. It says all things being equal a tyre will lose 1 psi per month (not per week), 2 to 3 psi over two or three months. I rest my case!

0/10 One hundred lines, I must read more carefully.