In my Defender I usually run equal ie 35 front and rear. Towing I'll bump the rears to 40, but it drives like a dray after the trailer is taken off, so back to 35 it goes.
Printable View
In my Defender I usually run equal ie 35 front and rear. Towing I'll bump the rears to 40, but it drives like a dray after the trailer is taken off, so back to 35 it goes.
Factory settings are based on the factory tyre.
They are too low in the front by a long shot.
Tyre pressures may require variation from brand to brand on the same vehicle, in the same size.
It also depends on accessories fitted etc...
A safe starting point is 10% above manufacturers placard if using same size.
I found this with BFG's A/t's,compared with XPC's,even unloaded.Quote:
Originally Posted by DiscoMick
Interesting then that LR have used the same (unladen) tyre pressures for the RRC, P38A, D1 (although slight lower on 235/70 tyres), and D2 from day 1 even with numerous versions of the factory fitted tyre.Quote:
Originally Posted by Tombie2
I see the Defender also uses 28 psi front but only 35 (vs 38) in the rear.
Hi Mick,Quote:
Originally Posted by DiscoMick
I understand that AT's probably should have higher pressures than HTs on the road because they generate more heat and with a LT constuction are a stiffer tyre.
When towing I also up the rear pressures a bit, especially if there is a lot of ball weight. I usually try to run little ball weight even for heavy loads as the rig handles significantly better. When there is a lot of ball weight it pushes the car around a lot at the rear which makes it unstable with most of the movement coming from the flexing in the tyre. The increased pressure takes a lot of this out and also increases the tyres load carrying capacity.
both my discos were the same when it came to tye pressure differences, they both liked 6 or 4 psi difference front to rear depending on loading.
one had std tyres the other 265's. had to run different overall pressures but the difference stayed the same. just seemed to me that it handled much better that way.
the tyre placard gives tyre pressures to make the ride comfortable....which will make the vehicle nicer to drive....
which will sell more of their vehicles......
they dont care that running pressures softer will wear the edges out and deem the tyres unroadworthy way before they are designed to last.....
neither do the tyre manufacturers......cos they just get to sell more of their product sooner.....
for better economy.....the tyres in most cases need to be run at higher than recomended pressures.....
by how much higher.....? well....that depends on each individual vehicle.....
heres an example of my own vehicle.....03 fender... the placard says 28 front and 38 rear.....
ive run them at 40 front and rear ever since i got the car new......they wore out nice and even across the tread......and i had them on for 80,000kms.....
and thats without rotating the spare in......
i only got rid of them because i had scored a new set of tyres.....they were worn low when i took them off......
but were still roadworthy....would have gone another 10 -20,000kms judging by the wear rate....
i recently pumped my tyres up to 45 front and 50 rear.....and found a huge difference in the ride with just 5 psi extra.....
it is a lot firmer and harsher.....i will drop them back down to 40 and leave them at that.....
of course.....off road pressures are a different story.......
and also.....different brands and constructions require different pressures to support the same weight.....
there are lots of cheap tyres on the market these days.....which are very very soft and flimsy.....
a word of warning though...... DO NOT exceed the maximum pressure stamped on the side of the tyre.......
and avoid running tyres too soft as they will overheat on long high speed runs and may delaminate.....
and that cant be fun at high speed......
NO, Philip, I didnt miss the point, whether its tyre manufacturers or vehicle manufacturers recommendations, it makes no difference, its still the knowledge of what your tyres actually do to your vehicle dynamics that I'm talking about.Dont assume you know it, if you really dont, then go to a reputeable training organisation and learn......it may save someones life.
advanced driver training schools arent going to give their syllabus away for free on their website, you have to book in to the school and do their course to learn their information. CDF isnt it?
Hmm, tyre placards.....
FWIW the placard in a 130 recommends 75psi in the rear AT ALL TIMES...
yeah, right....
Tyre type, tyre construction, suspension set up, driving conditions, road surface, speeds involved all have major bearings on the pressure required.
An example of construction difference is when I swapped from BFG MT's to Maxxis 762's.
Same size, but I needed to up my pressures by 8 psi to get the same contact patch/feel and even wear, they are that much more pliable in the sidewall.
As for the stability thing for advocating mis-matched pressures, unless it's peculiar to D2's I don't buy it unless it's peculiar to certain tyre types (construction).
On classic style coil suspension I've run tyre pressures even all round, higher front and higher rear and have never had a 'stability' issue with even pressures.