tyre pressure

Can anybody help????
Ive fitted a set of 20 inch rims to my new audi a3. they fit perfect and im using pirelli 235 30 20 P- ZERO NERO tyres !
i got a puncture in one and the tyre blew its wall , shortly after another 2 punctures. the tyres all failed before the tread got low the garage put 30-32 psi in at first and said maybe the psi was too low...
the next set i used 40 psi(max pressure is 50) and 2 blew out the same time and these tyres have only been on a week :( the 2 i had left have cracks on the walls like that of a tyre thats been on ages but my tyres still have the knobbles on and the tyre fitting paint....they have just gone down over night, the tyres would have worn in the middle on my old set if id over inflated and rubbed on the edges if under but the first set worn evenly and ive never had a nail in any of them......i know all the simple rules but i dont know where to turn and its costing me a fortune, ive just bought 2 new tyres last week and the walls have slit already, these tyres are gonna be the death of me if i dont get to the bottom of it
what on earth am i doing wrong? please help me!

I am assuming the car was fine before you put 20s on it?

Maybe 30psi is too much, my A6 takes 30 yet that has 235/45/17s. Either that or the wheels themselves are puncturing the tyres, it would be nice to know where exactly on the tyre that the puncture was.

Paul

Some where there is a way to identify the age of the tyre, I can't find it, I'm sure it was on some tyre website.

I think the tyres "might" be old stock from what your saying.

By the way Welcome to the forum.:beerchug:

The wheels are fairly new and the first set of tyres lasted nearly 75 % of tyre wear but then they just gave up and cracked .
There is a possibility that these tyres are old stock because these tyres are a very low profile and are not common at all.they are splitting on the walls after a few days.there are no nails or holes to cause the tyre to go down other than the cracks in the side walls also there is no puncture hole as you would normally find on the tread area.
do you think 1f a 17 inch is 30 psi....a 20 would be greater psi at say 40...or would the psi decrease to say 25???
Thanks for your help!

I may be talking rubbish, but surely the pressure in a tyre is related to the weight of the vehicle to the area of the tyre on the road. So if a 235 wide tyre is 30 psi for an A6, then with the A3 being lighter, the pressure should be less, not more.

As for tyres showing wear centre tread for over inflation, it would take some miles for this to show. From what you say you are hardly getting off your driveway before these are failing. I'd have a word with your tyre supplier - they seem sub-standard to me. Had your wheels been at fault, then your fitter would surely have said something.

You say the tyres fit perfect, well they might fit while the car is stationary but as you go over bumps the tyres could be catching the arches just slightly. What size have you taken off the car? You could try finding a speed hump or something and getting somebody to watch you over it to see what's happening.

Paul

Its really hard for me to give every detail without writing an essay lol
i would expect that most people who have this type of tyre on their car either dont go far due to the expense of replacing or have a super car that they dont do alot of miles in so never get the problem i have.. i would expect that a tyre that has been designed for toring cars should last a few trips on the public roads.
This is my car that i use for work, i could do 100 miles in a day sometimes.its not practical..i know but i love my car..i would expect to have each set of tyres for at least 10000 miles but after 3 or 4 motorway runs in a straight line...they are shot at :(
these wheels fit with no rubbing at all and were made and imported from holland even when everybody i spoke said they would never fit,i have a full turning circle without any rubbing, even at speed.
plus can anybody help me with the last question???? if i have a 19 inch tyre at 35 profile and say 30 psi --- will a 20 inch tyre with 30 profile have less or more pressure than a 19 . thanks again guys

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Originally Posted by martin007

Its really hard for me to give every detail without writing an essay lol
i would expect that most people who have this type of tyre on their car either dont go far due to the expense of replacing or have a super car that they dont do alot of miles in so never get the problem i have.. i would expect that a tyre that has been designed for toring cars should last a few trips on the public roads.
This is my car that i use for work, i could do 100 miles in a day sometimes.its not practical..i know but i love my car..i would expect to have each set of tyres for at least 10000 miles but after 3 or 4 motorway runs in a straight line...they are shot at :(
these wheels fit with no rubbing at all and were made and imported from holland even when everybody i spoke said they would never fit,i have a full turning circle without any rubbing, even at speed.
plus can anybody help me with the last question???? if i have a 19 inch tyre at 35 profile and say 30 psi --- will a 20 inch tyre with 30 profile have less or more pressure than a 19 . thanks again guys

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Answer to your last question, I would say slightly less, but only about 5 psi max. Probably about 2 or 3 psi I would have thought.

Paul

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Originally Posted by martin007

Can anybody help????
Ive fitted a set of 20 inch rims to my new audi a3. they fit perfect and im using pirelli 235 30 20 P- ZERO NERO tyres !
i got a puncture in one and the tyre blew its wall , shortly after another 2 punctures. the tyres all failed before the tread got low the garage put 30-32 psi in at first and said maybe the psi was too low...
the next set i used 40 psi(max pressure is 50) and 2 blew out the same time and these tyres have only been on a week :( the 2 i had left have cracks on the walls like that of a tyre thats been on ages but my tyres still have the knobbles on and the tyre fitting paint....they have just gone down over night, the tyres would have worn in the middle on my old set if id over inflated and rubbed on the edges if under but the first set worn evenly and ive never had a nail in any of them......i know all the simple rules but i dont know where to turn and its costing me a fortune, ive just bought 2 new tyres last week and the walls have slit already, these tyres are gonna be the death of me if i dont get to the bottom of it
what on earth am i doing wrong? please help me!

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Why don't you give Pirelli a bell and see what they say they must have a customer support department? 20's on an A3 is a large tyre but they seem to have run ok in the past. If i had a tyre fail after day's no way i'd be paying for a new set, they're clearly not fit to purpose

I rang pirelli today and they told that these tyres have never been tested as they are not standard fit on any production car.
they told me that ideally, i should not exceed standard size by over 3 %.
they said 19 s were the biggest i should go for safety, i spoze they are right but the 20 s look fantastic.
They also told me that i was exceeding the load on the tyres and my car was too heavy ...????... but if an a3 is too heavy and these tyres or made for touring cars... what car could they possibly go on ? they had no answer for that,There is no feedback on the tyre at all , no data at all, !!!! ? Mine is a 2.0 TDI a3!
I DONT GET IT AT ALL !

Quote:

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Originally Posted by martin007

I rang pirelli today and they told that these tyres have never been tested as they are not standard fit on any production car.
they told me that ideally, i should not exceed standard size by over 3 %.
they said 19 s were the biggest i should go for safety, i spoze they are right but the 20 s look fantastic.
They also told me that i was exceeding the load on the tyres and my car was too heavy ...????... but if an a3 is too heavy and these tyres or made for touring cars... what car could they possibly go on ? they had no answer for that,There is no feedback on the tyre at all , no data at all, !!!! ? Mine is a 2.0 TDI a3!
I DONT GET IT AT ALL !

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A TDI A3 will be much heavier than a touring car chief, why don't you get some tested tyres on either that or stop trying to rice up your car and slam it on some smaller alloys ;)

I'd have to agree. IMO I can't see 20" wheels looking good.... 19" would look very big on an A3. Your running racing rims on a street car, it's asking for trouble. If you like massive alloys then why not try 19".

It's not about the width of the tyre that determines pressure. The greater the volume of air, the less pressure is required. Bicycle tyres are what 50-60 psi and they feel soft. Tractor tyres support large weights and are typically 8-9 psi due to their massive size.

Paul B - it's odd how the A6 runs 30 psi on 235/45/17. I have the same on my A4 and it's 32 all round. I would have thought the A6 would be heavier!!! :aargh4:

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Originally Posted by Marco34

I'd have to agree. IMO I can't see 20" wheels looking good.... 19" would look very big on an A3. Your running racing rims on a street car, it's asking for trouble. If you like massive alloys then why not try 19".

It's not about the width of the tyre that determines pressure. The greater the volume of air, the less pressure is required. Bicycle tyres are what 50-60 psi and they feel soft. Tractor tyres support large weights and are typically 8-9 psi due to their massive size.

Paul B - it's odd how the A6 runs 30 psi on 235/45/17. I have the same on my A4 and it's 32 all round. I would have thought the A6 would be heavier!!! :aargh4:

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Pleased I read this, I would like alloys but cost prohibits me, I like the look of alloys but need comfort more than anything both the wife and I have damaged spines and bumpy rides are out the window, from what you've said I'll probably buy some 205 60 16 to replace the 195 60 16 that are on it now the 205's are an option on my car, would I be able to drop the PSI by a couple?

Quote:

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Originally Posted by Marco34

I'd have to agree. IMO I can't see 20" wheels looking good.... 19" would look very big on an A3. Your running racing rims on a street car, it's asking for trouble. If you like massive alloys then why not try 19".

It's not about the width of the tyre that determines pressure. The greater the volume of air, the less pressure is required. Bicycle tyres are what 50-60 psi and they feel soft. Tractor tyres support large weights and are typically 8-9 psi due to their massive size.

Paul B - it's odd how the A6 runs 30 psi on 235/45/17. I have the same on my A4 and it's 32 all round. I would have thought the A6 would be heavier!!! :aargh4:

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Dunno about the A6 running 30 psi being odd, i'll picture it tonight.

Paul