[anjan_c2007]

Originally Posted by NerdSpeaks

A quick observation : I feel that front & rear tyre pressures have got swapped in the chart. Usually, engine side gets more pressure. Or ?

Rightly pointed out by you but for cars only. The two wheeler column is though intact.

PAINTER'S DEVIL

[earthian]

Originally Posted by NerdSpeaks

A quick observation : I feel that front & rear tyre pressures have got swapped in the chart. Usually, engine side gets more pressure. Or ?

Not necessarily. The recommended pressures for my Mercedes C class is 28 psi for front tyres and 32 for back tyres.

[bravo82in]

Sorry for the noob question or if it has been answered before.
When we talk of tyre pressure, is it the cold tyre pressure in the morning or max pressure when car is running or something else?
Thanks and regards
Bravo

[Gupts007]

Originally Posted by bravo82in

Sorry for the noob question or if it has been answered before.
When we talk of tyre pressure, is it the cold tyre pressure in the morning or max pressure when car is running or something else?
Thanks and regards
Bravo

It's always cold tyre pressure. On hot tyres the tyre pressure will automatically go up so all measurements should be taken when the car has not run for a bit.

[Gansan]

Originally Posted by bravo82in

Sorry for the noob question or if it has been answered before.
When we talk of tyre pressure, is it the cold tyre pressure in the morning or max pressure when car is running or something else?
Thanks and regards
Bravo

Cold tyre pressure, with no occupants inside the car. If four people are sitting inside, the pressure reading will be wrong. And the pressure should be checked within a km or two after leaving home in the morning.

[Tvk1991]

I recently purchase a new A35 AMG in India.
The tyre specs as per Mercedes Benz are R18 with a 2 person occupancy front: 38psi and rear 31psi.
For 4 person occupancy front: 39psi and rear 35psi
On the day of delivery the 4 tyre were 42 psi and I drove close to 300kms until next tankful of petrol and correcting the pressure to 39 and 35psi. But after filling the manufacture recommendation I see the car bottoming on few speed breakers when compared to 42 all around.

Can I stick to 42psi all around, drive feel wise I don't see much difference when driving around at 42psi.

Please let me know your suggestions.

[Gansan]

Originally Posted by Tvk1991

Please let me know your suggestions.

Keep 2 psi more than full occupancy recommendation on all tyres, no more. We can never tell exactly when an additional passenger will be there and immediately correct air pressure.

Did you correct the tyre pressure immediately after doing 300 km? Then the pressure indicated will be wrong. Tyre pressure should be checked when they are cold. And nobody should be sitting inside while checking pressure.

Take the car to a fuel station within 2 km from your place and check the pressure after making everyone get out.

[zeng]

Originally Posted by Tvk1991

I recently purchase a new A35 AMG in India.
The tyre specs as per Mercedes Benz are R18 with a 2 person occupancy front: 38psi and rear 31psi.
For 4 person occupancy front: 39psi and rear 35psi
On the day of delivery the 4 tyre were 42 psi and I drove close to 300kms until next tankful of petrol and correcting the pressure to 39 and 35psi. But after filling the manufacture recommendation I see the car bottoming on few speed breakers when compared to 42 all around.

Can I stick to 42psi all around, drive feel wise I don't see much difference when driving around at 42psi.

Please let me know your suggestions.

I suppose the MAX tyre pressure indicated on your tyre sidewall is 51 or 44 psi.

On either scenario, 42 psi all round is fine and safe.

[Tvk1991]

Originally Posted by Gansan

Did you correct the tyre pressure immediately after doing 300 km? Then the pressure indicated will be wrong. Tyre pressure should be checked when they are cold. And nobody should be sitting inside while checking pressure.

No it was after driving a around 300kms (42 psi without scrapping anywhere) and fill petrol and air pressure early in the morning at my a fuel station <1km from home.

I have a air pressure monitor in my car and I reduced it to manufacturer recommended.

[aravind422]

Hi,

I need a bit of advice here. I have a 1st gen Innova (diesel). As most of us know, the recommended cold tyre pressures for the stock 205/65R15 tyres are 33 PSI all round for two persons.

I needed AT tyres for the roads (and ocassional dirt tracks) I drive on. So I got a set of 205/70R15 all terrains.

I would like to know what pressures would be optimum for these slightly taller tyres? I usually travel with just one or two passengers. And if the load increases for substantially longer rides, I have a tyre inflator at hand.

The tyre shop did recomended 35PSI all round, but could it be the other way around...
...same vehicle + larger tyre = lower pressure ??

One more thing, the ride quality is not much different from 33 to 38 PSI.

Thanks

[zeng]

Originally Posted by aravind422

The tyre shop did recomended 35PSI all round, but could it be the other way around...
...same vehicle + larger tyre = lower pressure ??

If the larger/newer tyre has higher Load Index (as embossed on the sidewall), YES.

[aravind422]

Originally Posted by zeng

If the larger/newer tyre has higher Load Index (as embossed on the sidewall), YES.

Thank you, and yes, the OE tyres had a load index of 94 and the new ones are rated 96.

[zeng]

LI 94 at 33psi (OEM) carries a load of 1411 lbs per tyre.

LI 96 at 29psi carries a load of 1422 lbs per tyre (higher than above) , hence may be selected for replacement tyre.

LI 96 at 35psi recommended by your tyre shop would carry a load of 1554 lbs per tyre, can one select this??

Why not?

Now can you select 38psi??

Of course you can.

[aravind422]

Originally Posted by zeng

Now can you select 38psi??

Of course you can.

Ok...
...THAT was quite a bit to digest

So, I now understand that 29 PSI is enough for the higher profile tyre, and that even 35 or 38 is not too much.

I occasionally have to drive 200 to 300 km's in a day. Given that I do get the front tyres aligned at proper intervals for this 1.6 ton (RWD with IFS) vehicle, I would love to know the correct pressure so that the tyres maintain an optimum contact patch with the road and do not suffer overheating or uneven wear.

Thanks.

[carreragt6]

Why does similar cars from same manufacturer carry very different pressure ratings.

Eg: Our ignis has a recommended psi of 36 in the front and 32 in the rear unloaded and cold

Our swift had recommended psi of 29 all around.