I have 205/65/15 fitted to my 420G, and having been running around 34psi cold
Is that a little high ?
what pressure are you XJ guys running
weather is mainly warm to hot here 20-35C
not many folks run 420G & the correct tyre for them is a 14" 80 profile tyre,
hence my question on the XJ list
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I use 32/34 front rear, Tony…
Your 34 is not ‘too high’ - but tyre pressure is a matter of preferred ride quality, stability, tyre wear, speed and load/car wight. And tyre characteristics…
Frank
xj6 85 Sov Europe (UK/NZ)
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As Frank says, also in my experience each tire, depending on brand, size, wall stiffness and of course weight of the car, has it’s own preferred optimal pressure.
I run the 215/60 R15 on my XJ12 at 36/38psi, a bit high, but it minimizes greatly tire wear.
The best is to observe tire wear, worn edges means under-inflated, presuming of course your alignment is correct.
Aristides
I use about 35 all around. That is slightly above the Jaguar recommendation for higher speeds but tyre wear is even and it’s not too soft. The “comfort” pressure was too soft for me and I didn’t like the handling. Also important to mention is that my tyres were cheap all-year ones so the ideal pressure varies. I imagine the MkX is heavier and might want a bit more than the XJ; if you can’t find Jaguar information, 32 front and rear might be a good starting point.
I found this in what I think is an old article: F, 28; R, 25 p.s.i. (normal driving) F, 28; R, 28 p.s.i. (full load) F, 32; R, 30 p.s.i. (fast driving) F, 32; R, 32 p.s.i. (fast, full load). It seems a bit low but maybe not. Just find your preferred choice and don’t go too low, just like with bicycle tyres.
thx gents, I feel reassured.
420G weighs 1778kg
squeels like a demon with tyre pressures at 30 or below, cant understand how Jaguar can recommend pressure as low as that
I’m sure ride comfort was a consideration.
And tires have changed a lot over the years.
Recommended pressure for many of the oldie USA cars was 24-26 psi with the old bias ply tires. Seems crazy now !
Cheers
DD
Or perhaps ending point!
Specialty cars and tires excepted, I’ve found that 32/32 works well on darn near any conventional passenger car for everyday-type driving.
Cheers
DD
I recall the “tyre placards” that were stuck to the inside of the glovebox door in the local products of my youth - different speed and load conditions and noted operating pressures. Comment was that they were all set for “ride comfort”. Jag recommdations are similar, I think, noting passage of 50 years. I run 34 all round on Pirelli 205/70 15s and front to rear rotate every 10,000 km. Paul
Tony,
SII OM specifies (front/rear):
27/26 < 100 mph 3 persons
27/30 < 100 mph full load
33/36 > 100 mph full load.
My car is specified to weigh 1740 kg.and I’m inflating to 40/40 with 205/70x15 winter tires and feel well. Plenty of comfort reserves in the suspension and no untowardly rattling yet.
Best
Jochen
75 XJ6L 4.2 auto (UK spec)
40/40! That’s too harsh for me. But when comparing to bicycles, more is okay: less is bad!
My exhaust rattles. Fix planned. Rest is fine, but 2.5 bar F/R are sufficient and I wouldn’t mind a little lower. Same tyres, somewhere around 1850kg kerb weight, at least this is the number that comes to mind on a Friday evening.-
What tyres do you run?
David
Admittedly, I only check once a year, so the average may be a tad lower;-), but that’s where I put it in summer.
Years ago I put on Nankang N-607 winter tires with a crystal. Very cheap and H rating lets me use the car all year long without limitation. In summer I drive with some more air, but at < 3000 mls/year I won’t use the tread. I was always satisfied, both in terms of comfort/noise and traction. They outperformed the ancient Pirelli P 4000 that came with the car by far. They are on their last season though.
Best
Jochen
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Hm, Tony - are you sure your suspension alignment is correct…?
there should be no squealing at that pressure, or lower - Jaguar sure would not recommend pressure, even below 30 psi, that would cause persistent squealing!
Might be a tyre characteristic - or your driving…
As an aside; it is not unusual to find different pressure recommendations from tyre and car manufacturers. Tyre manufacturers are concerned only with tyre performance - car manufacturers with ride comfort…
Frank
xj6 85 Sov Europe (UK/NZ)
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