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I've just bought a second hand VW Golf TSI. Great car.

The fuel flap shows the following tyre pressures in bar (1bar = 14.5psi): 

                    bar            psi
| Load       | Front | Rear | Front | Rear |  
| ---------- | ----- | ---- | ----- | ---- |
| 2 +luggage |  2.0  | 2.0  |  29   | 29   |
| 5 +luggage |  2.3  | 2.8  |  33.4 | 40.6 |

I have never had a vehicle where the fully loaded pressures are so much higher than the light-load pressures.

Typical journeys for me are evenly divided between just me and me plus three other adults.

I can't realistically inflate and deflate my tyres for almost every journey. So, where to set them?

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  • Welcome to Motor Vehicle Maintenance & Repair!
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Oct 14, 2017 at 16:21
  • Those are recommendations : some find a setting that they find comfortable for their driving style , road quality etc that they use - the average is a reasonable compromise. Also, the make of tyre also has an effect : some feel more compliant, some tyres seem to notice bumps more, some "tramline" more...
    – Solar Mike
    Oct 14, 2017 at 16:30
  • Thank you Paulster2, and @Solar-Mike -- much to think about there. I'm principally concerned about safety. But also, in some jurisdictions, being more than a given %age either way is illegal. In the past I have gone for the average, but +/-17% is a big range. Guess it's a consequence of the vehicle being quite light (1241kg).
    – AlanQ
    Oct 15, 2017 at 20:29

1 Answer 1

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In your case, I would set all pressures to 2.4 bar whenever inflating. The reasons are many-fold:

  • Tires lose some amount of pressure as a function of time. If you inflate to 2.4 bar, the next time you inflate it can very well be 2.3 bar.
  • Tires should ideally be rotated occasionally. Thus, setting e.g. 2.15 bar front and 2.4 bar rear means you have to adjust tire pressures the next rotation. I'm lazy and so I use the same pressures front and rear, even if the vehicle owner's manual might say otherwise.
  • Being over the stated pressure is usually not a problem. The tires typically can have a really high pressure. Just for fun, I once tested driving with maximum pressure as stated on the tire sidewall (which was probably something between 3 and 4 bar, I don't recall exactly because I don't have the test car anymore). Great for fuel economy, not so great for driving comfort.

So, because over the car manufacturer's recommended pressure is not a problem, your only problem is that the 2.4 bar pressure is lower than 2.8 bar recommended for full load at rear. I don't think for 4 adults the 2.4 bar at rear would be a too low pressure by a huge margin. The car supports a load of 5 adults plus heavy luggage. If you have only 4 adults and not so heavy luggage, 2.4 bar should be barely enough. If you are not convinced, you could raise the pressure to 2.5 bar. Note that 2/3 of 0.8 bar difference is 0.533... bar, and you have only 2/3 of the full load at rear, meaning 2.533... bar rounded to 2.5 bar will be enough for your maximum load.

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