Tyre Pressure: Nissan Auto: 38 PSI

38psi is for high speed running - quite normal.

Any help?

Chris

Simon Dean ( snipped-for-privacy@simtext.plus.com) gurgled happily, sounding much like they were saying :

I think you need to learn how to read it...

There's four sets of pressures on there.

1. (top left) Normal use - F 35, R 32
2. (top right) Normal load, high speed - F 38, R 35
3. (bottom left) Fully loaded - F 36, R 36
4. (bottom right) Fully loaded, high speed - F 41, R 38 (again, not applicable in the UK)

The high speed pressures don't really apply for UK use - they're for SUSTAINED 110+mph, so autobahn use only - even then, it's debatable whether you'd need to chuck that extra in.

I very much doubt you're running the thing fully loaded at all times.

So - Front 35psi, Rear 32psi, and chuck a little more in the back if it's your turn to be driving the local pie-eating club on their annual holiday.

Quite where you're getting your combination of 38/36 from, gawd alone knows...

Well if you look at that picture again (and this really is quite hilarious), the tyre measurements has "185/65 R14 85-86H" on the left, with "195/60 R14 85V" on the right, so a quick scan down reveals for normal load, ahh, 38/35 (rather than my mistaken 38/36). And that should be good over 112mph too... so I don't get anywhere near that, so perfect!

But yes, I see it now, thanks... how stupid was I? 38 psi for OVER 112 mph. 35psi for upto 112 mph...

Thank you.

I hope I provided you with some entertainment.

Cya Simon

(stupid stupid stupid stupid - can't believe I did that)

Simon Dean ( snipped-for-privacy@simtext.plus.com) gurgled happily, sounding much like they were saying :

After all, the tyre pressure cockup's an easy one to make.

Buying a slushomatic Primula, otoh... Nothing'd surprise us after that...

The 185mm and the 195mm inflated to the same psi are safe, but there is a better strategy. For the same load (total weight of the car and its occupants), the wider tyre by comparison has a stunted 'foot print' (reduced major axis of an ellipse) of tyre mark, coincident with a lower tension (stretch) in the rubber. To take advantage of this, it's usually advised to opt for a *lower* psi; the tyre is squashed such that the tension is increased to equal that in the slimmer tyre. (That also explains why a wider tyre of the same composite rubber generally has a higher load rating) The resultant larger 'foot print' gives better traction (on dry roads), and surely this is the prime consideration in choosing a wider tyre; it is pointless otherwise. By how much reduction in psi can be found in the Load and Inflation Table put out by the tyre manufacturer.

When I had a manual 94 2.0 Primera I experimented with tyre pressures over a

5 yr period and 35/32 was the best for handling on new 195/60's but the front tyres on OEM 5.5" wide steel wheels wore more in the centre, 33/30 seemed best all round for an unloaded car at UK speeds, very even wear and still sharp handling. Wheel widths can change everything though as the tyre shape becomes different.

I've tried 32psi (garage recommended pressure), and, maybe its the Barum tyres, but they feel sludgy and slide too much underneath. 38psi, while rickety, to me, give a very definite response at the front end and I prefer that.

I can't remember also, but I've had less wear problems at 38 than I have had at 32.

I'll try with 35psi though i think...

Thanks Simon

The 'placard' clearly shows the different pressures depending upon loading and maximum speeds. A garage will just give a compromise one.

What's so difficult to understand about that?