Tyre pressure 16 inch

[merc230ce]

Hi all,

My tyres are 16 inch 205/55 and inside the fuel cap the pressure stated is 29psi, so i went to the petrol pump and inflated the tyres to 29. this seems a little low to me? or am i mistaken. (i recently bought the car and pressure in tyres was 34!)

Hope someone can advise me.

Thanks

 

[mstar]

my 1998 c class, c250 td states 30f, 33r so i would guess urs is ok, as diesels normally have more psi. My tire pressures are in the petrol cap for 2 passengers.

 

[tom7035]

Hi all,

My tyres are 16 inch 205/55 and inside the fuel cap the pressure stated is 29psi, so i went to the petrol pump and inflated the tyres to 29. this seems a little low to me? or am i mistaken. (i recently bought the car and pressure in tyres was 34!)

Hope someone can advise me.

Thanks

The pressures as indicated inside the fuel flap are the ones to use. Slightly higher pressures will be indicated with a full compliment of passengers. Tyre pressures should be checked when thoroughly cold.

 

[mstar]

for the technical guys.... is there any difference to fuel economy/ride/acceleration having slightly more/less PSI -just out of interest

 

[matthewwillmottuk]

Fuel economy improves the higher the pressure, probably because the contact patch and therefore the rolling resistence decreases. However, I think actual grip starts to reduce dramatically above a certain point, to the point of becoming dangerous. Acceleration? More grip with lower pressure, so greater chance of wheelspin with overpressurised tyres.

Hey, I actually managed to answer a question with my first post!!! Don't worry - it won't happen often!!

Matthew
1980 380SL

 

[jberks]

Keep it up Matthew!

The only thing I would add / explain is that the higher the pressure, the more rounded the contact area of the tyre becomes and hence, as stated, the lower the contact patch. This matters, not only for grip, but as more work handled by the centre part of the tyre (the sides being effectively lifted out of the way), the more the centre of the tyre will wear. So, too high a pressure and you'll have perfect tyres at the sides but bald tread in the middle.
Lower the pressure and the reverse is true.
I tend to start with a compromise of the figures on the filler and then monitor wear and adjust accordingly to even it out.