pigeonfish Posted July 26, 2004 Report Share Posted July 26, 2004 Hi After a shock at the weekend (both rear tyres down to 10psi) I went to inflate and realised that there is no note on the recommended tyre pressures for my car on the door pillar. I have 235 / 40 / ZR18 wheels and carry only light loads, any help would be greatly appreciated. Also, I need to replace my Pirelli P-Zero Rosso tyres on the front, any recommendations for cheapo sites ? (tried mytres.co.uk and they come out at about £140 each delivered not fitted) Link to comment Share on other sites More sharing options...
Ari Posted July 26, 2004 Report Share Posted July 26, 2004 Crikey the elusive PF! Hows it going mate? Think the tyre pressures are inside the petrol filler cap. Link to comment Share on other sites More sharing options...
pigeonfish Posted July 26, 2004 Author Report Share Posted July 26, 2004 Hi Ari ! Hope you're well. I've been busy admiring all the A4 Cabs on the roads nowadays that and tending to the newborn - it ain't that easy getting car seats into the back without the roof down, therefore I am having to leave missus at home when I go anywhere and putting junior int he front ! quick thought - at what age are babies 'cabrio with roof down' safe d'ya think ? Thanks for the advice, not sure what's going on with the rear tyres - surely can't have 2 slow punctures ? i'll check the cap out, ta. Link to comment Share on other sites More sharing options...
brn7y Posted July 26, 2004 Report Share Posted July 26, 2004 The 18's on mine are 36psi with light loads. Link to comment Share on other sites More sharing options...
pigeonfish Posted July 28, 2004 Author Report Share Posted July 28, 2004 thanks for that, i'll up the psi - might mean I get a little more wear out of the tyres now ! Link to comment Share on other sites More sharing options...
Ari Posted July 28, 2004 Report Share Posted July 28, 2004 I had a look inside my filler cap this morning whilst I was cleaning it, and there is a sticker in there but it relates to type of fuel not tyre pressures, sorry! Link to comment Share on other sites More sharing options...
Scotty Posted July 28, 2004 Report Share Posted July 28, 2004 How do I describe it...here goes. On the saloon the pressures are just below the door latch on the frame that the door fits in to. i.e. not on the door but the .....err no thats not working.....follow the door sill towards the back of the car and it goes up towards the roof. 1/3 of the way up if the latch and the pressure sticker....errr it's still not clear is it. Someone else have a go. There's gotta be a simple way of explaining it! Link to comment Share on other sites More sharing options...
Hants_Cruiser_UK Posted July 28, 2004 Report Share Posted July 28, 2004 [ QUOTE ] How do I describe it...here goes. On the saloon the pressures are just below the door latch on the frame that the door fits in to. i.e. not on the door but the .....err no thats not working.....follow the door sill towards the back of the car and it goes up towards the roof. 1/3 of the way up if the latch and the pressure sticker....errr it's still not clear is it. Someone else have a go. There's gotta be a simple way of explaining it! [/ QUOTE ] Errrmm in the drivers door jam, just below the catch Link to comment Share on other sites More sharing options...
cosmicblue Posted July 28, 2004 Report Share Posted July 28, 2004 OK Boys that bit of the car is called the 'B Post', working backwards then; the front door hinges are on the 'A post'....get the idea? Link to comment Share on other sites More sharing options...
Hants_Cruiser_UK Posted July 28, 2004 Report Share Posted July 28, 2004 [ QUOTE ] OK Boys that bit of the car is called the 'B Post', working backwards then; the front door hinges are on the 'A post'....get the idea? [/ QUOTE ] Actually, I thought they were called "A pillar", "B pillar" etc.... Link to comment Share on other sites More sharing options...
Ari Posted July 28, 2004 Report Share Posted July 28, 2004 Yup, with HC on this. The door frame bit is the door jam, the pillars separating the windows are A pillar, B pillar etc. Link to comment Share on other sites More sharing options...
pigeonfish Posted August 3, 2004 Author Report Share Posted August 3, 2004 That's great if you have the standard 16's, but there is no pressure for 18's listed on the sticker in the door jam. However, I have the info after contacting the dealership and I was very, very surprised ! For 235/40/R18 the pressures are normal load front 39psi (2.7 bar) rear 35psi (2.4 bar) heavy load front 42psi (2.9 bar) rear 42psi (2.9 bar) that's alorra pressure, and I think I may verify this. For info, 2 tyres fitted (Pirelli P-Zero Rosso) £157 each, got a nice new scratch on the alloy thrown in for free, along with the worlds most obvious balance weight. It's going back tomorrow ! That and the tyre pressures were wildly different and I am checking the torque settings today after a scary report in the week before lasts Auto Express. Link to comment Share on other sites More sharing options...
iantate59 Posted August 4, 2004 Report Share Posted August 4, 2004 [ QUOTE ] That's great if you have the standard 16's, but there is no pressure for 18's listed on the sticker in the door jam. However, I have the info after contacting the dealership and I was very, very surprised ! For 235/40/R18 the pressures are normal load front 39psi (2.7 bar) rear 35psi (2.4 bar) heavy load front 42psi (2.9 bar) rear 42psi (2.9 bar) that's alorra pressure, and I think I may verify this. For info, 2 tyres fitted (Pirelli P-Zero Rosso) £157 each, got a nice new scratch on the alloy thrown in for free, along with the worlds most obvious balance weight. It's going back tomorrow ! That and the tyre pressures were wildly different and I am checking the torque settings today after a scary report in the week before lasts Auto Express. [/ QUOTE ] Your dealer isn't entirely right. The attached photo is the data sticker on my wife's A4 Cab. It shows 36 PSI for front and back tyres with a normal load and 42 PSI front and back for a full load with 18-inch wheels. Link to comment Share on other sites More sharing options...
pigeonfish Posted August 5, 2004 Author Report Share Posted August 5, 2004 Top man, thanks for that. I will go back to my dealer and question where they got their figures from. Is your car a UK model ? Strangely 17"'s are not listed on the sticker ? thanks again for your help. Link to comment Share on other sites More sharing options...
Big_Dan Posted August 5, 2004 Report Share Posted August 5, 2004 I think the 18s were on from new - hence the sticker ... the 16s will be for winter tyres on a spare set of rims. (M&S) Link to comment Share on other sites More sharing options...
iantate59 Posted August 5, 2004 Report Share Posted August 5, 2004 [ QUOTE ] Top man, thanks for that. I will go back to my dealer and question where they got their figures from. Is your car a UK model ? Strangely 17"'s are not listed on the sticker ? thanks again for your help. [/ QUOTE ] Yes, the car is a 2004 UK model. The eighteen-inch wheels were ordered as an option and, presumably, fitted at the factory. Link to comment Share on other sites More sharing options...
peterb Posted August 5, 2004 Report Share Posted August 5, 2004 [ QUOTE ] that's alorra pressure [/ QUOTE ] Bear in mind that (assuming the weight of the car doesn't change significantly) that an increase in tyre pressure means that you have less rubber in contact with the road. So, as an example, if you currently run 35lbs/sq.inch in your 16s, and you run the 18s at 40lbs - that's a 14% increase in pressure. This means that you will have 14% reduction in contact patch area! Link to comment Share on other sites More sharing options...
iantate59 Posted August 5, 2004 Report Share Posted August 5, 2004 [ QUOTE ] [ QUOTE ] that's alorra pressure [/ QUOTE ] Bear in mind that (assuming the weight of the car doesn't change significantly) that an increase in tyre pressure means that you have less rubber in contact with the road. So, as an example, if you currently run 35lbs/sq.inch in your 16s, and you run the 18s at 40lbs - that's a 14% increase in pressure. This means that you will have 14% reduction in contact patch area! [/ QUOTE ] Isn't a 235 tyre 14.6% wider than a 205? So the contact area would be the same. Link to comment Share on other sites More sharing options...
peterb Posted August 5, 2004 Report Share Posted August 5, 2004 [ QUOTE ] [ QUOTE ] [ QUOTE ] that's alorra pressure [/ QUOTE ] Bear in mind that (assuming the weight of the car doesn't change significantly) that an increase in tyre pressure means that you have less rubber in contact with the road. So, as an example, if you currently run 35lbs/sq.inch in your 16s, and you run the 18s at 40lbs - that's a 14% increase in pressure. This means that you will have 14% reduction in contact patch area! [/ QUOTE ] Isn't a 235 tyre 14.6% wider than a 205? So the contact area would be the same. [/ QUOTE ] No - the size of the contact patch has nothing to do with the size of the tyre. Making the tyre wider merely changes the shape of the contact patch. The area of the contact patch is a function of weight on the wheel and tyre pressure: Weight on wheel / tyre pressure = contact area. Link to comment Share on other sites More sharing options...
molegm Posted August 6, 2004 Report Share Posted August 6, 2004 my january 2003 3.0 cabriolet has got factory fitted 18" 9-spoke alloys and the tyre pressure plate on the B-Pillar says 42psi front and rear for light load (2 pers plus some luggage) and 47psi front and rear for full load am totally confused now! what is correct? Link to comment Share on other sites More sharing options...
iantate59 Posted August 6, 2004 Report Share Posted August 6, 2004 [ QUOTE ] my january 2003 3.0 cabriolet has got factory fitted 18" 9-spoke alloys and the tyre pressure plate on the B-Pillar says 42psi front and rear for light load (2 pers plus some luggage) and 47psi front and rear for full load am totally confused now! what is correct? [/ QUOTE ] I cannot clear up the confusion, but the photo I posted (ie 36/36 PSI and 42/42 PSI) is from an 1.8T FWD model. I am wondering if yours is a 3.0 quattro model? Heavier enginge and rear axle? Only guessing. As the eighteen-inch wheels are a bit rarer, what about you guys with seventeen-inchers (oooh, err!). Do 1.8s, 2.4s, 2.5TDIs and 3.0s all have the same pressures front and back with seventeen-inch wheels and what about quattro vs non-quattro? A bit nerdy, I know, but now I'm curious. Link to comment Share on other sites More sharing options...
Sven Posted August 6, 2004 Report Share Posted August 6, 2004 Repair manual says: The correct inflation pressures for summer tyres are listed on the sticker on the lower passenger's side B-pillar. <ul type="square"> Notes: [*] Please note that the inflation pressures listed on the sticker apply to cold tyres. When the tyres are warm, the actual pressures will be higher, but must not be reduced. [*] When using winter tyres, pressures should be increased by 0.2 bar. So I'd stick to the sticker for your specific car. (pardon the pun). There is no absolute rule you should start counting passengers and franticly adjust the pressure accordingly. Stay between the min-max pressure, and see what you like best for handling. I tend to keep mine a bit on the high side, a few notches under 'full load' indication on normal driving (2 peeps + bits & ends). When we go travelling with the usual sh*tload of luggage, I give it a bit extra (within limits of course). Just make sure it's even and not too low (or too high). Link to comment Share on other sites More sharing options...
jdehoogh Posted August 6, 2004 Report Share Posted August 6, 2004 [ QUOTE ] quick thought - at what age are babies 'cabrio with roof down' safe d'ya think ? [/ QUOTE ] For that case, I think the airbag on/off is a more serious issue. Top down would matter IMO. Link to comment Share on other sites More sharing options...
molegm Posted August 8, 2004 Report Share Posted August 8, 2004 tailpipe. my car is a front wheel drive 3.0 sport. unfortunately the quattro was not available when i bought mine and i do not particularly like front wheel drive cars! (previous cars were 2 TT roadsters and a Boxster S) But, Hey, if i had the quattro then i would not have the multitronic box....which i DO like, especially with the steering wheel gear buttons. I run my car on the pressures it asks for and do not have any problems. Link to comment Share on other sites More sharing options...
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