Thread: tyre pressures with bull bar

17 inch ko2's. No bullbar. I generally use 43-45 for the tar. It's a big heavy car. 36 is ok , 33 is too low for fronts imo. Each to their own I suppose.

I have ARB steel bar on the front plus rear wheel carrier and long range tank under the rear. I'm in Kalgoorlie - temperature is currently in low 40's. Checked TPMS this morning when I was out - all 4 are currently sitting on 40psi and spare is at 45psi. If I am heading out of town on a long run, I will pump all 4 on road tyres up to around 43 - 45psi.
Have been running Mickey Thompson STZ's up until recently (18 inch rims) and now running Toyo Open Country - would never run this vehicle at lower than about 38psi under any conditions.

Bars don't add as much weight as you think, I remember tombie saying about a 20kg difference

I have always run 32.5 psi on my D2 td5 . It is comfortable ride and I have never had wear issues.
I think the door placard mentions something about 27 psi which seems silly.
Going above 32.5 Give a very much harsher ride to me.

Here's another two bob's worth (shillings) for millenium members :0)

Low pressure wear is on both shoulders not just one. Too high pressure is in the centre. Tyre wear (note tyre not tire) on one side (shoulder) is normally an alignment problem. Scolloping is shockies.

Vehicle manufacturers always set up a vehicle's tyre pressures to give "understeer", not for optimum tyre wear or vehicle "control". Why understeer.............and very simply: If average punter is going too fast into a corner natural reaction is to take foot off. Doing so will cause the nose to tuck in and go around. In front wheel drive vehicles understeer can get to a point where it is referred to as "terminal understeer".

Increasing pressure increases grip, lowers rolling resistance.

Suggest you use either 4psi or 6psi test for correct tyre pressure. 2psi rule/test is for "P" tyres and 4 for LTs.

Ergo: check/set tyre pressure cold, run until tyre is hot say 30km (with an appropriate load) and check pressure.

if the pressure has risen less than 2psi for Ps or 4psi for LTs the tyre pressure is too high, if it has exceeded 2psi for Ps or 4 for LTs then the original/set pressure is too low. Uhhhh! Yep! Contra-indicated.

If pressure rise is too low tyre is running "cool" too much air. If pressure rise is too high, tyre is underinflated and running too hot (excessive deflection)

Running cool not a real problem, better grip less rolling resistance better fuel economy but centres wear.

Hot running is a disaster. Heat kills tyres, caused by excessive "deflection". Heat will cause hidden delamination inside the carcass. The tyre will not necessarily fail at the time but at the later "Mystery" blow out, tread separation. Most punters blame the "crappy" brand, not the long time ago or continual excessive deflection of the tyre.

Cheers

RF

Another thought:

If tyres are found with outside shoulder wear, it is obvious that those tyres will have been running underinflated/over deflected for a considerable period of time. The tyre carcass will be damaged with invisible internal delamination. My advise would be to replace those tyres.

Cheers

RF

When I took delivery of my 5th Disco (1 Series 2 TD5, 2 x Series 3 TD2.7, & 2 x Series 4 SDV6) just before the Series 5 disaster hit the market, the salesman gave me two excellent pieces of advice based on his extensive experience in the Land Rover service area. The first was to use sport mode for improved fuel economy (and that works by about 1.0l/100km), but the second was to always run the tyres at 40PSI all round. In the Series 3's and the first Series 4 the original factory rags never lastedmore than 40K. These ones look likely to exceed 50K. I have always run with an alloy bull bar, fridge and rear cabinet work, and I am not hard on tyres, having got in excess of 80k on General Grabber replacement tyres and similar on brake pads. It seems that the slight increase in harshness is more than offset by the improved tyre wear.

I have a 2015 Disco fitted with an East Coast heavy duty alloy bullbar. I run tyre pressures by the book. I only got 40,000 km out of the original Goodyear Wranglers but the wore out evenly after being rotated every 10,000 km or so.

I am about to replace my Pirelli Scorpian ATs that are just nudging 80,000 km (also evenly worn out) with Scorpian AT Pluses which certainly look the goods!

About half of my mileage is towing a 6.5M boat!