Rich Posted January 14, 2014 Report Share Posted January 14, 2014 I'm sure I've asked this before but can't find anything. My question is as the thread title really, what's the ideal temperature to adjust tyre pressures? I increased mine a couple of weeks ago first thing in the morning (7am) and always do them at home, I never drive the car to a garage. In the past I've noticed a difference in the readings between checking them first thing and then again in the afternoon when it has warmed up slightly. Quote Link to comment Share on other sites More sharing options...
liner33 Posted January 14, 2014 Report Share Posted January 14, 2014 They don't need to be that precise imo Quote Link to comment Share on other sites More sharing options...
Tony Posted January 14, 2014 Report Share Posted January 14, 2014 Ambient temperature is best and i don't mean 3am in frost but the average temp in your driving environment. Quote Link to comment Share on other sites More sharing options...
Sagitar Posted January 14, 2014 Report Share Posted January 14, 2014 They don't need to be that precise imo I agree. I have said before that there are far too many variables in "domestic" driving for tyre pressures to be a precise science. The important thing is to check regularly and ensure that they do not become under-inflated. Tyre wear is a good guide to inflation levels (if you use common sense). Quote Link to comment Share on other sites More sharing options...
Rich Posted January 14, 2014 Author Report Share Posted January 14, 2014 I agree. I have said before that there are far too many variables in "domestic" driving for tyre pressures to be a precise science. The important thing is to check regularly and ensure that they do not become under-inflated. Tyre wear is a good guide to inflation levels (if you use common sense). Tyre wear doesn't happen overnight though, it takes time, unless your geo is miles out! I have noticed the change in handling with a 2psi difference and I've seen greater differences than that when checking pressures in the early morning compared to the afternoon. I think I will check/adjust them during the day from now on. The reason I asked is when I had the winter tyres fitted they inflated them to 30psi but when I checked them they were around 27psi. I don't think it was my gauge as I've not had a difference like that before. I increased them to 32psi before our trip but I have a feeling they are probably higher than that if I check them when it's warmer. Anyway, Tony has answered my question, so I will adjust the pressures during the day rather than early morning. I suppose in the warmer months it doesn't matter too much when they are done. Quote Link to comment Share on other sites More sharing options...
liner33 Posted January 14, 2014 Report Share Posted January 14, 2014 You can't feel the difference that's in your head . Tyre temp changes when you start to drive in them , hence the need to check cold Quote Link to comment Share on other sites More sharing options...
Tony Posted January 16, 2014 Report Share Posted January 16, 2014 Nitrogen Quote Link to comment Share on other sites More sharing options...
Rich Posted January 16, 2014 Author Report Share Posted January 16, 2014 I'm not so sure, I've felt the difference in the steering before when adjusting pressures by a few psi, it does change how the tyres perform IMO. Quote Link to comment Share on other sites More sharing options...
liner33 Posted January 17, 2014 Report Share Posted January 17, 2014 It does change how the tyre perform yes , can you feel it on a road car ?? Doubtful Quote Link to comment Share on other sites More sharing options...
Tony Posted January 17, 2014 Report Share Posted January 17, 2014 Within reason the manufacturers tyre pressures are only a suggestion. Manipulation +- a few PSI is required most times in my opinion. They might suggest a "normal" pressure and then a "loaded" pressure, well how loaded, how many people and what weight should they be? How much fuel do i need in the car? Then they suggest Motorway pressures, well at what speed. Is it the same for summer and winter? There's to many variables to assume the listed pressure is the law. So within reason the correct pressure needs to be found. Quote Link to comment Share on other sites More sharing options...
Rich Posted January 17, 2014 Author Report Share Posted January 17, 2014 I'm going to check them over the weekend and see what they're reading now, I reckon they will be higher than what I put them on. Interestingly Honda recommend setting the front higher than the rear unless you have a full load. On every other car I've had they recommend they're the same or the rear is higher. Is this down to the Accord being heavier? Quote Link to comment Share on other sites More sharing options...
Tony Posted January 17, 2014 Report Share Posted January 17, 2014 The rear is very light by comparison to the front. Don't get me wrong peeps the manufactures put a lot of time a money into suggesting the correct pressures but the suggestion cannot encompass all. Quote Link to comment Share on other sites More sharing options...
Rich Posted January 17, 2014 Author Report Share Posted January 17, 2014 I'm wondering if the length of the car has anything to do with it? Obviously alot of the weight is at the front with the engine/drivetrain and the wheels are alot further back than that of the Corolla, Mondeo and Escorts I had. Quote Link to comment Share on other sites More sharing options...
parthiban Posted January 17, 2014 Report Share Posted January 17, 2014 What's the weight distribution for the accord? It must be heavily front biased for that to make sense - if true it must have fairly understeery handling! Quote Link to comment Share on other sites More sharing options...
Rich Posted January 17, 2014 Author Report Share Posted January 17, 2014 What's the weight distribution for the accord? It must be heavily front biased for that to make sense - if true it must have fairly understeery handling! I don't know, would the handbook say? Actually I've not noticed any understeer but then I've not really pushed the car yet. It handles very well for a boat on stilts though! Quote Link to comment Share on other sites More sharing options...
Tony Posted January 17, 2014 Report Share Posted January 17, 2014 It's wheel-base really helps. Quote Link to comment Share on other sites More sharing options...
Rich Posted March 18, 2014 Author Report Share Posted March 18, 2014 On Sunday I checked my pressures after having the new tyres fitted. One side of the car had been sitting in the morning sun, the other in the shade. The tyres on the sunny side were warm to touch, the other side cold. I asked for the pressures to be set at 31psi and when I took readings from the sunny side they were 36psi! The tyres in the shade were 32psi so I will definitely be checking them when it's cloudy or before the sun has risen now. Quote Link to comment Share on other sites More sharing options...
Tony Posted March 18, 2014 Report Share Posted March 18, 2014 This is where Nitrogen inflation steps in....... Reads like the guys used compressed air Quote Link to comment Share on other sites More sharing options...
Rich Posted March 18, 2014 Author Report Share Posted March 18, 2014 This is where Nitrogen inflation steps in....... Reads like the guys used compressed air I thought they always used compressed air and nitrogen was extra? Quote Link to comment Share on other sites More sharing options...
liner33 Posted March 18, 2014 Report Share Posted March 18, 2014 That 20% makes all the difference Quote Link to comment Share on other sites More sharing options...
Rich Posted March 18, 2014 Author Report Share Posted March 18, 2014 It does if you want to adjust the pressures. What if I thought they had been set too high, dropped them 5psi and then later on when it's cooled down they'd be 26psi instead so under-inflated. Quote Link to comment Share on other sites More sharing options...
parthiban Posted March 18, 2014 Report Share Posted March 18, 2014 It does if you want to adjust the pressures. What if I thought they had been set too high, dropped them 5psi and then later on when it's cooled down they'd be 26psi instead so under-inflated. Might be wrong but I think liner's comment was in reference to the fact that there is roughly 80% nitrogen in air, so there's only an extra 20% when using nitrogen inflation. I'm surprised by that pressure hike though, especially from a car just sitting in the sun and not being driven in anger on track or anything. Quote Link to comment Share on other sites More sharing options...
Rich Posted March 18, 2014 Author Report Share Posted March 18, 2014 Ah that makes sense, I didn't know that. I doubt the lads put the wrong pressures in so I'll check them again one morning before the sun is out to see what they are. The tyres were noticeably warmer than the other side though. Quote Link to comment Share on other sites More sharing options...
liner33 Posted March 18, 2014 Report Share Posted March 18, 2014 Also pressure rise isn't linear , just dropping 5 psi won't work But yes air is already 78% nitrogen If the car is parked in the sun the pressures will go up Quote Link to comment Share on other sites More sharing options...
Sagitar Posted March 18, 2014 Report Share Posted March 18, 2014 If they were the same to start with and one side was shaded and the other very sunny, you would see a difference no matter what gas they were filled with. The change in pressure is proportional to the change in temperature, but the temperature is measured in degrees Kelvin so the change would be relatively small. If there was a lot of moisture in the air used to inflate the tyre the difference would be greater (because water vapour is not an ideal gas) but for nitrogen and unadulterated air the change would be exactly the same. For example, if the shaded temperature was 15C and the sunny temperature 35C, that translates to 288K and 308K or a difference of just under 7 percent. With a cool side pressure of 32 psi, the sunny side pressure would be just over 34 psi. But the tyre is not completely inelastic so a small part of the pressure increase would be lost in increasing the internal volume of the tyre. As liner said or implied, it's all a bit academic for a domestic vehicle because differences of these magnitudes are generated all the time we are driving. There are just too many uncontrolled variables acting to change the temperature of the inflating fluid. 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.