Car Tyre pressures - Difference from 3 pers to full load ?(no inbetween)

Okay bit of a random thread here, but i've not been able to find any info about this little thing thats bothering me.

I'm doing a big road trip to the South of France from Saturday and getting all set up for the trip.

I want my car tyre pressure to be suitable for a fairly full load and having trouble deciding on what pressure to run at.

The car is a Mazda6 Sport and the handbook says..

1-3 persons =32psi front/ 32psi rear

Full load = 38psi front/ 46psi rear

There is no scale or any intermediate pressure to run, if say you are somwhere in the middle weight wise.
I assume full load to be 5 persons and a full boot.

There will be 3 persons and a full boot for this trip, the Missus, the boy (9), me and 3 suitcase/holdalls.
So basically 2.5 persons and a boot of luggage.

What psi should I run at, full load ? or maybe somewhere in the middle ?

We will be doing some lenghty drives on the trip in one go so i'd like the tyres to be optimum if I can.

Any car genius gurus about ????

 

46 psi seems really high.

I don't know what year yours is, but a google search on a 2014 shows maximum payload is 1,043 lbs. I doubt you'll be carrying anywhere near that. 35psi on all 4 tires would probably be more than sufficient.

 

Sorry typo, its 45psi not 46 !!

I double checked with the sticker inside the door and that just matches what the handbook says..

1-3 persons =32psi front/ 32psi rear

Full load = 38psi front/ 45psi rear

Its a 2012 model and the 2.2d engine, so quite heavy but still 45psi is alot.
Tyres are rated to 50psi though.

 

Split the difference? 35/38?

 

I'd say 36 all around. If you go too high it will be an uncomfortable ride. If you're going on roads where you can go 140+ go 38 psi. This is cold tyre pressure, if you're checking at a servo it might be inaccurate due to warm tyres and mistreated equipment. If checking with a gauge, a good gauge like a PCL brand (English brand) if you can still get them would be advisable. They're by far the best I've seen.

 

45 is more than most tires maximum. Most are rated for 44 PSI MAX.

I run 35 PSI at all times, and it's a nice balance between ride quality and gas mileage. There's no way you can load a small car down like that enough to where it won't be sufficient.

 

I was surprised as well but...

 

Well ain't that bizarre. Is that just some attempt to compensate for over-rated struts and coil springs or what?

 

Low profile tyres require higher pressure.

 

I wouldn't call 205 60R16 "low profile" by any means.

 

Yeah 35psi has been mentioned a few times now i'll go with that. Cheers for the suggestions guys.

The tyres are Michelin Pilot Sport 3 225/45R19 91W and rated to 50psi.

I guess a Mazda6 is a small car on that side of the Atlantic, here its probably considered quite large !!

 

I agree at the 35psi figure. A good balance in both ride quality/comfort and efficiency...

Sorry, just to add something to this post instead of opening a new one!

It's car related so it should be ok. Quite a few of you know previously how many bizzare and annoying issues I've had with my current vehicle.

Usually I'm visiting the local garage several times a month for small issues here and there. The longest I've EVER gone without making any trips to the garage was 4-5 months, UNBELIEVABLE....

All issues are small, minor, annoying but cheap...

It is however very inconvenient since I need a car on a daily basis to get me to the office. Buses and trains are a no go since my company is situated in a desert with nothing nearby. Heck even the nearest petrol station is a 15 minute drive.

Local shops or even a place to eat is also 15 minutes away...

Bottom line you need a car or your fucckked...

Anyway, previous recent issues that occurred and were solved include:

Front left flat tyre - One morning it was almost flat having metal wires visible from the thread of the tyre. When driving to the nearest tyre shop (thankfully it was a 5 minute drive from where I live) I change the tyre and got it balanced. Small problem, however it was immediately rectified...

Coolant - I'd find myself almost every week filling the coolant only noticing it's almost empty after several days of driving. We found out the water pump was cracked hence the leak. This was fixed. No more leaking!

Transmission/Gearbox fluid - Once again there was a small leak going on for many months, possibly over a year! It was however so minor you wouldn't notice. Anyway, the tranny fluid was drained and freshly refilled and gasket filter replaced. Next to the filter, there is a small black tap, forgot the name but that was responsible for the leak. It cost around $2 for the part causing the leak!!!

EPC light - An ongoing problem been happening over a 2 year period. Currently it is under control but at times it can display itself. Last time I saw the light was 2 weeks ago. Simply starting the car in the morning triggered the fault when going to work. The usual trick gets rid of it, and that is by turning off the engine for a minute or so and trying again...

Since almost everything has been changed in the engine, the only option is to change all the electronic wiring in the engine since the previous wiring was poorly put in and needs changing. It does not cost a lot and neither does it take time to install. Problem is finding a set! A new engine loom set from Audi/VW will cost something stupid like $400-$500.

However, should I find a used set or one removed from a damaged/totalled car should cost around $100-$200 for a clean/decent set.

I was told to visit a few scrapyards to try a find a compatible set. Worst case scenario, I'll have to buy a set online from abroad should I not find one locally.

This is not guaranteed, but changing all electric wires in the engine should prevent any more EPC warning lights as well as having the car run better, smoother and more economical...

Limp mode (stuck in third gear) - This is the most recent issue which only started two days back. The day prior to that, the car would randomly get stuck in third gear when driving. In the beginning I could turn off the engine and turn it on again and it would be fine. After several minutes it would get stuck again...

The next day, same issue, after 30-40 minutes of driving it was stuck in third gear. This time it was worse. Even when turning off the engine and restarting, it remained stuck in gear. Heck after several hours it was stuck in gear.

Yesterday I drove all the way to work in third gear. It was such a horrible and uncomfortable drive. I was on the high way in the sixth lane doing 70-80 km/h and the engine screaming at 3500 rpm...

Doing 90-100 km/h results in the car doing over 4000 rpm. This is putting extreme pressure & strain on the gearbox especially when starting off from a traffic light...

Strangest thing was on the way back home yesterday, after 15-20 minutes, the gear suddenly shifted from the third to the fourth gear!

I was so happy and before anything else went wrong I went from 80 km/h to 140-150 km/h and doing around 4000 rpm...

As usual, when I got closer to my house, the car again got stuck in the third gear. After speaking to the mechanic to book it it, he informed me he was busy and has no time to look at the car. Until Friday/Saturday he's fully booked.

This morning I simply got my mother to drop me off to work. I drove to my mothers home using the slow route full of traffic lights and maximum 80 km/h limit so the car can reach without being abused...

After explaining the issues with the stuck gear, he mentioned 2 possible causes for the so called stuck in third gear/limp mode.

1 - It must be connected to a computer to diagnose and address the exact cause. Without checking, you cannot be 100% sure.

2 - It could be the gearbox/speed/engine sensor that has fuukked up and needs replacing.

3 - Gearbox Lubrication - Not gearbox/transmission fluid but some lubricant which is added inside the gearbox, where all the teeth and metal contacts are. I believe he has to remove the external gearbox cover to add the lube. It's not a big job, only the gearbox cover is remover, where you have the park, drive and reverse option near the shifter.

Sorry for a long and boring post. Just thought I'd share the latest car troubles I've had over the recent months...

Anyone have any input with regards to the limp mode/stuck in gear 3 issue? Based on what I said what do you think?

 

Sh*t dude sounds like you are having a bit of a nightmare with your motor.

What car and engine is it?

I was chatting to a taxi driver the other day who had a VW Passat diesel. We were discussing the pros cons of complicated diesel engines vs good old petrol. We both agreed that when they work well the diesels can be great, but if you start getting problems..... they can be an expensive pain (DPF filters, High pressure fuel rails, Turbos, EGR's etc etc)

Long story short he mentioned his car (which was a 2013 model) kept going into limp mode, getting stuck in 3rd gear.
He said his mechanic couldn't find the problem yet but stopping and restarting always solves the issue...temporarily.
He's resigned to taking it into VW main stealer at some point for them to diagnose.

Feel for you dude.

Ps. Do you have a OBD2 bluetooth adapter ? If so you can check for fault codes yourself on your phone with Torque BHP app

 

Oh no It was meant more a general remark about why tyre pressure recommendations can very a lot.

I agree with the 35 PSI recommendation, as long as this is the cold tyre pressure, NOT checking it at a servo!

 

Thanks for the response. My car is a 2003 Audi A3 1.6 Petrol, Automatic...

Unfortunately I do not have a bluetooth adapter to check for fault codes. However, on friday I'm visiting the mechanic who will then run a computer check to see the given fault.

It really is a pain in the ass having issues such as being stuck in third gear.

Just to get to work and back is a 3 hour drive on a daily basis! I cannot have a car consistently pissing about causing delays when getting to work and back.

I'll report over the weekend with any update I get...

As of now I'm sticking to slow/normal roads full of traffic lights which limit my maximum speed to 80 km/h...

Otherwise I'm usually on the motorway doing between 100-125 km/h...

 

I just PRAY to god there is no damage to the gearbox. If there is, then looks like the car will be sold as scrap since it's not worth the repair...

Tomorrow morning I'll be going to the garage to get it checked. He mentioned some kind of oil/lubricant which he will add to the gearbox/transmission fluid.

The additive, apparently, may solve the issue of the stuck gear. There is a 50% of success according to this mechanic!

Otherwise we'll see what else it may be...

That's all for now guys. I'm off to the garage at 9:30am tomorrow...

 

Sounds to me like an electrical problem -- your gearbox has a controller module (TCM) so I would look at that first before puttng additives into the gearbox. It's likely got multiple sensors plugged into it so possibly one of those or the TCM itself is faulty, or one of the connectors needs a good cleaning. If the TCM gets an erroneous reading from one of the sensors it will go into limp mode and won't be able to switch gears.

As it's an intermittent problem I'd suspect a loose/bad connection on one of the plugs.

 

Thanks morbias, I'll get the mechanic to check the electrical connections...

 

Ok. Here is the update. There were two main issues, both resolved as of now.

1 - Fuel pump was fuucckked. It was not properly pumping through the car, the circulation of fuel was poor. When the car was scanned, one of the faults was low fuel pressure. A fresh fuel pump was installed. This took care of the first problem.

2 - Stuck in third gear (limp mode) . As said before, a simple additive was added to the transmission fluid. After reading the box, it simply ensures better circulation of transmission fluid as well as lowering temperatures by 6-10 degrees. It looked like a quality product and it did work wonders! The car shifts up/down butter smooth and all is good at the moment.

Recently, another minor issue popped up, hopefully a minor one. The air conditioning is making a strange noise and not cooling. I hope it needs gas and not a compressor replacement!

Tomorrow morning I'll let a local garage check the a/c gas and see why it's not cooling.

 

Didn't you replace the fuel pump once already? I really hope you're not ever letting the gas gauge get below 1/4, especially in a desert environment.

Regardless, if I had that many problems I'd never touch an Audi again. At this point I'd learn to start doing your own diagnostics and repairs, or find a different vehicle. Transmission additives are never a long term solution.