Tyre Pressures for Comfort

Mk2 3.4
Vredestein Classic tyres. Background then a question.

Currently running 30 psi all around (quite why I don’t know / recall, but no matter).

I don’t have an airline so before I hog one of the few accessible forecourt airlines and burn through a number of 50p pieces, I was going to reduce to 25 psi rear, 28 psi front, which is as per manual for general driving, not laden, not sustained high speed use. Reason for doing so is comfort - the roads around here are dreadful and getting worse; akin to a demonic washboard. Not withstanding all the economy / grip / tyre life factors, how much difference does a reduction, in this case by a 1/6th at the rear, less than a 10th at the front make to comfort? I just thought I’d ask before experimenting directly.

Fwiw, i increased from 30 to 35 and it’s noticeable.
You can of course reduce pressure without airline and decide when it’s enough; do you have any pressure gauge?
If you overshoot you can still correct that.

David

“You can of course reduce pressure without airline and decide when it’s enough; do you have any pressure gauge?” Indeed - dubious of the accuracy but all things are relative, plus still have the one in the tool kit! Thanks for the comment.

Suggest getting a quality gauge like this : https://www.summitracing.com/parts/joe-32307/overview/
Mine has proven to be very accurate. It has a bleed valve which helps for setting pressure accurately.
Also a compressor is very handy : this is the one I have : https://www.amazon.co.uk/Viair-00074-Heavy-Portable-Compressor/dp/B01N33MPKO/ref=sr_1_4?ie=UTF8&qid=1522678124&sr=8-4&keywords=tyre+compressor+viair

Thanks Mark, good advice, although I am reluctant to add to the pile of ‘stuff’ we have - we have our home, garage, sheds, office - all seemingly occupied to a greater or lesser degree with ‘stuff’. There is only two of us plus a cat - sometimes I wish I could just get a skip and be done with all the unnecessary detritus of life - I might start with the financially draining and emotionally nil return cat.

(I mean the furry one, not the Jag.)

The wiff and I are doing that: no kids to whom to leave it, and a great deal of stuff that only folks my age want.

We call it, *house cooling.

:wink:

My work is often dealing with ‘the stuff’; is it cold to suggest we should shuffle off with little more than we came in with?

Born wiff nuthin: aiming to cark it, the same way!

Knowing that our Jaguars were built with bias ply tires the pressure specs in the books would be for such tires. I have always run at 32 psi and things seem to work well. I also rotate the tires every few thousand miles and remove the spats and hub caps before I let the local tire monkeys mess with the rotation. I keep a close eye on them as they are likely to cause serious problems using the wrong nut wrench or over torquing. My recent purchase of a mini in house lift will now allow me to rotate on my own . I notice that the local oil change places seem to way over inflate the tires saying that the cold weather will lower the pressure. Somewhat true but in our commuter car which is driven mostly at highway speeds, their initial high pressure would cause rather higher pressure at speed and a rough ride. On this side of the pond, one can go to Discount tire for a free pressure check and they even fix flats even though you may have bought the tire elsewhere. It is so much easier to lower to your desired pressure than mess with adding, checking, etc.

I had to toss tires with only 10K on them and plenty of tread left as they were ten years old and unsafe at that age.

Gerard
Using Yokohamas currently and very happy with their performance.

That’s why I bought the softest gumballs for Tweety: I knew they’d age out, long before wearing them out, if not.

Might I ask you to specify ‘softest gumballs’?

Sounds a bit naughty!

Gerard

Tires with the lowest UTQG rating, for treadwear: On toys, I want sticky, not longevity!

The Yokohama AVIDS I ran on Tweety lasted about 4 years/set, before needing replaced, and that is perfect!

HAD i kept it, I was going with the even-softer Kumhos.

What sizes / spec do you order?

By the way, reduced pressures to 28 front, 25 rear on the Vredesteins - no noticeable impact to steering weight and welcome improvement to comfort all around. New rear springs next week (Owens) and are there any suggestions for front springs apart from the usual suspects, sorry, I mean usual suppliers?

Not entirely sure of exactly what Kumho offers, but it would have been 205/60s.

As for torsion bars, Ill assume any that are least expensive will work fine: personally, Id only fully trust that which SNG Barratt sells.