best tyre pressure for tarmac

07 hillux coupla dogs, jerry cans and a swag

allterrain bfg's (forgot that piece)

Agree. For BFG All Terrains 40 all round. 42-44 at the back if heavily loaded. 22-25 on dirt, 60kph. 15 on sand, though I don't do much sand driving.

(These are all cold pressures, and I use the 4 PSI rule)

Cheers

Frank

Frank
I fully agree

Cheers Bucky

Frank
Sorry mate
My pressures are hot

Cheers

its a simple question, some say 32psi as it makes a smoother ride, tyre manufactures say 36psi, and the other theory is 40psi for less tyre wear but a bumpier ride. i spend as much time off the tarmac as possible but with a 3100km trip i thought i would see differing opions

I would start off at 40 psi and experiment up or down from there. Ride comfort is a personal thing and it also depends on your suspension.
With 3100klms you have plenty of time to find the sweet spot.

OH...as for speed.... makes no difference, tyre preasures on road vehicles are not varied with speed within the legal speed limits.

There are variation table for some tyred that give different load and preasure ratings, but they are either way below sensible or way above legal road speeds.

But an extra 2 or 3 psi never hurt anybody.

cheers

"OH...as for speed.... makes no difference, tyre preasures on road vehicles are not varied with speed within the legal speed limits."

Hmmmm......

Have a look at this document researched by a member and posted in his blog. In particular the second link in the main page - 4WD Light-Truck Tyre Load-Speed-Pressure Charts.

Cheers

I have no idea where the bloke who did that reasearch got his information, and note that it does not have a wide range of tyre sizes.

It may give an indication of how a tyre performs in an off road aired down state...and we should all be restricting our speed when aired down

BUT it would only be applicable off road.

The manufacturers and the standards manual are clear......there is 1 recomended table of load V preasures for each tyre and the speed applicabe is all legal road speeds...and then some.

If your tyres are not inflated at least to the preasures recommended on the tyre plackard or from a published load V preasure table for that tyre your vehicle is defective........and probaly dangerous.

Recommended tire preasures for road vehicles are not varied with speed within legal road speeds.

cheers

I am the bloke (a Professional Engineer) who did the research, and if you care to read the whole article you will see that all of the information comes from the tyre manufacturers or the US Tyre and Rim Association who develops specifications for US tyres (and conducts testing). Much of the information is quite hard to find on the internet but you will find links to most sources.

Although the curves were constructed for only handful of common tyre sizes, there are about 80 to 90 different tyre sizes listed in the tables as well as the method of producing the curves.

I say again that the information in the link posted is for tyres in off road use, and the top speed in any of the graps is 104Km/h ( 65 miles per hour)


On Australian roads we have to have all our vehicles and especially TYRES fit to travel at the maximum permitted road speed plus a safety margin.

From memory the minimum speed rating for tyres fitted to pasenger and light commercial vehicels in australia is "S" or 180Km/h.

The Australian Standard, does list recommendations for increases in tyre preasures for high speeds, but they begin at 160Km/h

the standard lists a recomendation for a 5psi increase over the standard recomendations in tyre preasure for speeds above 160Km/h and less than 210Km/h.

So our standard recomended tyre preasures are good for 160Km/h.

So on the tarmac there is one recomended minimum cold inflation preasure for a given tyre at a given load.

There is no variation in the recomendation for for legal speeds on public roads.

But a 2 or 3 extra PSI never hurt any one.

cheers

As I tried to get through on my first post, none of this information is my 'opinion' it is all from authoritative sources.

The information on the link is for Light Truck tyres "Used On Improved Surfaces" not off-road.

If you care to follow some of the links provided you will that Goodyear recommends a pressure increase of 10psi for speeds between 106kph and 121kph for Light Truck tyres.

I think part of the issue here is the use of american documents.

The americans do and permit all sorts of stuff that are not done here, all you have to do is look at some of the weird vehicular arrangements on the roads over there.

In this country all our recommended preasures are designed on maximum permitted highway speeds...and that is what is leggaly binding.

I highly recommend the Tyre and Rim Association of AUSTRALIA standards manual, it can be purchased from the association for $50 posted while the print run lasts.....but remember like most standards it does not contain the whole story.

There was a time in the early days of radials that some vehicle manufacturers recommended different preasures for round town and highway use in this country.....this was also a period where we had lots of problems with radial tyre failures.

All that is past, and I have not seen a recent tyre plackard in this country that has any change of tyre preasure for speed.

There are similar tables for load v preasure, increases and decreases in speed and load, up to 165% increases in load and speeds up to 210Km/h applicable light truck tyres the australian manual, in the main they are not intended for pasenger and light commercial use on public roads.

You may also note that there are many load ratings and speed ratings covered in the manual below and above what would be legal on australian public roads.

It remains that under Australian, regulations, conditions and standards there is one set of reccomended minimum inflation preasures for a given tyre..and overriding all is that information printed on the tyre plackard

The load V preasure v speed information in both the linked documents and in the asutralian and US manuals are however valuable for off road use.

and as has been stated in the linked document, a great many people will be exceeding the capacity of their tyres when aired down.

cheers

It must also be understoog that there are a great many applicatons for tyres that are off public roads.

Areas such as docks, loading yards, mine sites and private haul roads would all be considered "improved pavement".

The specifications and data in the manuals and provided by the manufacturers is specific to the tyres and mechanical applications in isolation.

Road rules, vehicle manufacturer specification & engineering design and design australian rules must be considered in addition.

cheers

I have never had 4WD tyres that were made in Australia to Australian specifications. I have only ever had US tyres made to US specifications. I believe that the Japanese tyres are also made to US specifications.

There is also the European Tire and Rim Technical Organisation (ETRTO) which sets standards for European Tyres.

Do we still make any tyres in Australia?

Oh now this is getting interesting.

I have compered a few of the pieces of data from the linked document by Rob D.

The tables in the australlian standads manual, agree with the Toyo tables in the linked document with only minor variations, and they also agree with the 104Kp/h line in the graphs.
I only checked a 285/75/R16

But what is interesting is that the Australian documents clearly indicate the standard tables are good for 160Kp/h

The increased speed table for light truck lists speeds up to 160Kp/h as zero increased preasure required.

and interesting indicates a 6% tyre preasure increase for a 5% load increase at limited speed of 100Kph.

I have not seen any infrmation on load v reduced preasure in the standard.

cheers


very interesting.
No personal attack intended, but I am interested in the difference in the figurers.

Regardless of where they tyres where made, unless they where grey imports they will comply with the australian specifications.

Besides I do not beleieve that there will be any difference between tyres of the same size profile and construction regardless of the origin.

Copper Australia are keen to point out thought that some grey imported coppers may not be up to specification on certain vehicles, but that is because they are the wrong model for our requirements.

cheers

Mate I have tried the 4psi rule on my vehicle and it comes up with preasures way below the recomended tyre preasures from the published tables.

Lots of people rave about the 4psi rule, but sorry it can not be accurate, there are too many variables.

It may seem to work with some tyres on some vehicles, but as soon as you get to the outer limits of what is "normal" some considerable variations occur.

cheers

These are cold measurements.