Skateboard Neutral Newbie February 14, 2012 Share February 14, 2012 Did a tyre rotation today. At the tyre shop, the workman inflated the tyre to 30PSI as per manufacturer guideline, but when the tyre is out of the car. Is this correct? Or should the 30 PSI be set when the tyres are on the car already, bearing the weigh of the car? Or no difference?? ↡ Advertisement Link to post Share on other sites More sharing options...
Quantum 5th Gear February 14, 2012 Share February 14, 2012 Did a tyre rotation today. At the tyre shop, the workman inflated the tyre to 30PSI as per manufacturer guideline, but when the tyre is out of the car. Is this correct? Or should the 30 PSI be set when the tyres are on the car already, bearing the weigh of the car? Or no difference?? what car is it? 30PSI is quit low, normal it's 33PSI Link to post Share on other sites More sharing options...
Yixiang1 3rd Gear February 14, 2012 Share February 14, 2012 when u car is cold just drive to the nearest petrol station to pump the pressure u want lor... Cold tyre pressure more accurate. I tend to prefer Esso... most of them have digital pumps, except a few old ones... Link to post Share on other sites More sharing options...
5936 1st Gear February 14, 2012 Share February 14, 2012 It does not matter on or off load. As long as it is inflated according to Car's tyre inflation recommendation for the particular tyre size, it is correct. Care to share what car is it? Link to post Share on other sites More sharing options...
GoodCar 4th Gear February 14, 2012 Share February 14, 2012 Did a tyre rotation today. At the tyre shop, the workman inflated the tyre to 30PSI as per manufacturer guideline, but when the tyre is out of the car. Is this correct? Or should the 30 PSI be set when the tyres are on the car already, bearing the weigh of the car? Or no difference?? When the tire is loaded with the weight of your car, the tire pressure will increase Link to post Share on other sites More sharing options...
Kiadaw 6th Gear February 14, 2012 Share February 14, 2012 what car is it? 30PSI is quit low, normal it's 33PSI Mine is 36 front, 30 at the back, base on manufacturer recommendation. So its not low. But I guess its depends on many factor, for instant, the setting I quote earlier is for 3 adults, if 5 adults, there is another setting. There is also different setting for Winter & summer tires. Anyway, I need to inflat my tires soon. Its been more than 3 weeks since I last inflated mine. Last 2 days I tried to inflat my tires, but one of the petrol station, the hose was not there, & the other 2 I visited have no pressure pump in sight. Link to post Share on other sites More sharing options...
Ithunk 1st Gear February 14, 2012 Share February 14, 2012 34 all round depending on the make and the model of the vehicle Link to post Share on other sites More sharing options...
SimonTan 2nd Gear February 15, 2012 Share February 15, 2012 That is so so wrong! The tyre is rigid and in elastic. The steel belts do not allow the inside volume to change much. In real world situation, the on wheel and off wheel pressure will remain the same, or if you want to argue at least negligible to measure using the common pressure gauge. When a tyre manufacture recommend the tyre pressure. It is of course when it's unloaded pressure. Pressure will only increase IF the total internal space is reduced while still holding the same amount of air. That will never happen for a rigid car tyre! The tyre may flex, but the steel belts are keeping the total internal volume constant. When the tire is loaded with the weight of your car, the tire pressure will increase Link to post Share on other sites More sharing options...
Nooby Clutched February 15, 2012 Share February 15, 2012 For a 15' Tyre Mistubishi Lancer, how much is the air pressure needed? Link to post Share on other sites More sharing options...
Skateboard Neutral Newbie February 15, 2012 Author Share February 15, 2012 Thanks for all the feedback! Based on what I have been reading as well, think I managed to convince myself that there is no difference whether it is loaded or unloaded. PV = nRT As n, R and T remains constant and V is largely unchanged, the pressure (P) inside the tyre is also largely unchanged, whether it is loaded or unloaded. Link to post Share on other sites More sharing options...
Skateboard Neutral Newbie February 15, 2012 Author Share February 15, 2012 BTW, I am driving an Altis. Link to post Share on other sites More sharing options...
Topspin 2nd Gear February 15, 2012 Share February 15, 2012 Did a tyre rotation today. At the tyre shop, the workman inflated the tyre to 30PSI as per manufacturer guideline, but when the tyre is out of the car. Is this correct? Or should the 30 PSI be set when the tyres are on the car already, bearing the weigh of the car? Or no difference?? For all my previous tire replacement, I always drive it home then immediately release some air until it is the pressure I wanted. The correct pressure should be when the car weight is acting on the tire. I have wanted to know how much will the tyre pressure increase with and without tire load. I suppose I will just experiment is myself. Could not find the answer on the Internet. Tire shops tend to over inflate the tire. I believe it is because they do not want to be responsible if the tire blows out due to under inflation on our first drive out of the shop. They will ensure the pressure they use is for high speed driving (usually above 170 km/hr). It becomes very uncomfortable. For singapore roads, we do not need to fully comply with the high speed tire pressure. Normal speed pressure can be up to 8 psi lower than the high speed tire pressure. Link to post Share on other sites More sharing options...
Topspin 2nd Gear February 15, 2012 Share February 15, 2012 (edited) That is so so wrong! The tyre is rigid and in elastic. The steel belts do not allow the inside volume to change much. In real world situation, the on wheel and off wheel pressure will remain the same, or if you want to argue at least negligible to measure using the common pressure gauge. When a tyre manufacture recommend the tyre pressure. It is of course when it's unloaded pressure. Pressure will only increase IF the total internal space is reduced while still holding the same amount of air. That will never happen for a rigid car tyre! The tyre may flex, but the steel belts are keeping the total internal volume constant. Don't fully agree. Have you tested this yourself, i.e. test the pressure with and without the weight of the car? All pneumatic tires will flex when loaded. When V in the equation PV=nRT reduces, the P will increase. Tire looks semi rigid because the pressure is keeping it round and nice. If an external load is added to the tire, the pressure inside the tire will increase correspondingly to maintain the nice round shape otherwise it will collapse, until the point the air pressure will burst the tire from inside out.(explode, NOT implode) Edited February 15, 2012 by Topspin Link to post Share on other sites More sharing options...
Ternghuei Neutral Newbie February 15, 2012 Share February 15, 2012 pump air into tyres when its cold. Link to post Share on other sites More sharing options...
GoodCar 4th Gear February 16, 2012 Share February 16, 2012 Hi tire temp cause by side wall flexing due to under inflation is the main killer for tire. Overinflation will subject tire structure to un necessary load Link to post Share on other sites More sharing options...
Zesty Neutral Newbie February 16, 2012 Share February 16, 2012 pump nitrogen still the best! =D Link to post Share on other sites More sharing options...
GoodCar 4th Gear February 16, 2012 Share February 16, 2012 (edited) That is so so wrong! The tyre is rigid and in elastic. The steel belts do not allow the inside volume to change much. In real world situation, the on wheel and off wheel pressure will remain the same, or if you want to argue at least negligible to measure using the common pressure gauge. When a tyre manufacture recommend the tyre pressure. It is of course when it's unloaded pressure. Pressure will only increase IF the total internal space is reduced while still holding the same amount of air. That will never happen for a rigid car tyre! The tyre may flex, but the steel belts are keeping the total internal volume constant. Good argument Wonder why the decal at the side of the car door specify higher pressure for higher load? Reduce the flexing? Edited February 16, 2012 by GoodCar Link to post Share on other sites More sharing options...
Camrytron 6th Gear February 16, 2012 Share February 16, 2012 BTW, I am driving an Altis. Bro ur tyre is 15" rite?can pump 30-32psi is ok.. My camry only pump 32psi in order to enjoy more comfort.. Pump high nothing much different in fc n dnt feel good too.. ↡ Advertisement Link to post Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In NowRelated Discussions
Related Discussions
Goodyear Eagle F1 Asymmetric 6
Goodyear Eagle F1 Asymmetric 6
Poor Worksmanship from Tyre Workshop
Poor Worksmanship from Tyre Workshop
Spare tyre carrier for Renault Grand Scenic
Spare tyre carrier for Renault Grand Scenic
Tourador Tyres
Tourador Tyres
Tyre puncture
Tyre puncture
Seeking advice: can the tyre still hold?
Seeking advice: can the tyre still hold?
Yokohama Advan Apex V601
Yokohama Advan Apex V601
Recommended Tyres for EVs by Experience
Recommended Tyres for EVs by Experience