stevie_b Posted July 17, 2009 Share Posted July 17, 2009 What would say is the maximum safe tyre pressure to inflate tyres to? I've got a Ford Fiesta with standard wheels and tyres (I think they're 14"). They're fairly new tyres, the oldest is about 4 months old The recommended tyre pressure is about 32 psi I think. I inflated them to 38 psi (to get better fuel economy), and my girlfriend's just had a puncture whilst driving. The tyres are all of a decent make: Dunlop/Falken on the back and Falken on the front. I would think the tyre should be able to have taken 38psi: if I inflated them to low to mid 40s, then I'd expect them to suffer blowouts/punctures etc. What do you think? Is 38psi too much to ask when the recommended is (IIRC) 32psi? Quote Link to comment Share on other sites More sharing options...
Thorin Posted July 17, 2009 Share Posted July 17, 2009 If the recommended is 32psi... I'd inflate them to 32psi. But I wouldn't have thought 38 would make much difference. Quote Link to comment Share on other sites More sharing options...
keancy Posted July 17, 2009 Share Posted July 17, 2009 32psi for a Fiesta Tyre I only have 30psi all round in my "Big" Falkens sat on my Supra. Am I to low then? Quote Link to comment Share on other sites More sharing options...
absz Posted July 17, 2009 Share Posted July 17, 2009 maxium tyres pressures are normally written on the sidewall of the tyres in very small lettering. Quote Link to comment Share on other sites More sharing options...
Lbm Posted July 17, 2009 Share Posted July 17, 2009 32psi for a Fiesta Tyre I only have 30psi all round in my "Big" Falkens sat on my Supra. Am I to low then? I'm 36psi all round on mine (9 years and still going...) Quote Link to comment Share on other sites More sharing options...
Wez Posted July 17, 2009 Share Posted July 17, 2009 For road use I have 36psi front and 34psi rear on a MKIV. Tyre pressures are normally on a sticker inside the door area or on the huge notice by the air pump at the station Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 17, 2009 Author Share Posted July 17, 2009 (edited) But would you expect to have a blowout caused by overinflation to 38psi? I wouldn't, but I don't know much about tyres and what they can/can't take. I will certainly look at the sidewall to check the maximum pressure. If it's below 38 then I guess I was asking for it. What I'm trying to avoid is blowing through a series of tyres due to over-inflation, whilst trying to get the best possible safe fuel economy. I could just leave the rest of them pumped up to 38 and "wait and see", but that could prove expensive. Edited July 17, 2009 by stevie_b (see edit history) Quote Link to comment Share on other sites More sharing options...
Jake Posted July 17, 2009 Share Posted July 17, 2009 Low tyre pressure is more of a cause of blowouts than over-inflation. But, over-inflating tyres to improve fuel economy is really not a good idea because the tyre will wear out more quickly and also the wet weather grip will be badly reduced. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 17, 2009 Author Share Posted July 17, 2009 Thanks for the advice all. The RAC guy who changed the wheel for her found a big piece of metal sticking out of the rubber! We have our culprit! I'll still check the maximum pressures though to be on the safe side. Quote Link to comment Share on other sites More sharing options...
martini Posted July 17, 2009 Share Posted July 17, 2009 Thanks for the advice all. The RAC guy who changed the wheel for her found a big piece of metal sticking out of the rubber! We have our culprit! That makes more sense! I'm on 34psi all round. Quote Link to comment Share on other sites More sharing options...
Lbm Posted July 17, 2009 Share Posted July 17, 2009 That makes more sense! I'm on 34psi all round. For your Supe, or your Fiesta? Quote Link to comment Share on other sites More sharing options...
martini Posted July 17, 2009 Share Posted July 17, 2009 For your Supe, or your Fiesta? In my Supe. The fiesta is only 3 weeks old and is my little lady's. She's not done the tyre pressures on it yet, maybe she will in a few weeks. Only been on the road for about 200 miles so far! EDIT: (not sure if the new and old fiesta would have the same recommended PSI btw) Quote Link to comment Share on other sites More sharing options...
movistar Posted July 18, 2009 Share Posted July 18, 2009 If your girlfriends really fat then 38 psi might be alright but otherwise stick to the recommended pressure's...laden and un-laden do differ so check your manual. Oh if she really likes under steer go a bit higher;-) Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 18, 2009 Author Share Posted July 18, 2009 The maximum pressure is 51psi on that tyre, so that's well within its limits! I looked it up in the Haynes manual. About 30psi unladen, and 41psi (!) fully laden. I was surprised there was that much difference. Quote Link to comment Share on other sites More sharing options...
Kirk Posted July 18, 2009 Share Posted July 18, 2009 people on this forum make me laugh! 28-34 psi is all you ever need on the roads depending on weight load on the wheels then you crank it up a little bit more Quote Link to comment Share on other sites More sharing options...
Kranz Posted July 19, 2009 Share Posted July 19, 2009 I run my tyres on my focus at 50 psi hot with the TPMS showing tyre pressures and temperatures. Wear is very low and is even due to less tyre heat than when lower inflated. The more a tyre flexes the more it heats up and the more it wears. Its actually a myth (from crossply days) that a tyre will 'crown' in the middle at high pressures. It actually stays flat due to the radial belts holding it in shape..... like its supposed to! Run the tyres at the max sidewall pressure (either 44 or 50 psi) checked when hot. Ride will be a bit rougher, and handling will be slightly worse, but rolling resistance will be much lower. Puncture susceptibility is slightly increased, but in most cases if you drive over a sharp object its unlikely that the tyre will conform around it, so you would probably have got a puncture anyway. If you really want to lower the rolling resistance to next to nothing then fit the new Michelin Energy Saver tyres and inflate to the max sidewall pressure (51psi IIRC). You'll see a difference! The official line from tyre companies is that they do not have data to support or condemn this practice as they don't test tyres at the max sidewall in real world conditions...... but the max sidewall pressure is there as the pressure to use at the tyre's max safe load (weight) at the rated speed, so if its at this pressure with a lower load then it can only be safer For more info on hyperinflating tyres then see http://ecomodder.com/forum/showthread.php/hyperinflating-tires-2582.html Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 19, 2009 Author Share Posted July 19, 2009 Kranz, some good info there! That's basically why I'm running the tyres above the recommended psi. Quote Link to comment Share on other sites More sharing options...
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