Thread: my tyre pressure experiences

As "pigheaded Dutch selfdeared Tirepressure specialist, I think I can add to the discusion here.

In opening post you come to 59%, but calculate pressure using 49%, a miswriting I think.

But the lineair calculation you use is not that bad, gives slightly higher pressures then the official european calculation from ETRTO, wich I got hold of end 2007, and went running with.
Now use my own determined formula ( better ofcource) closer to linear calculation.

Have an old list of Michelin with pressure/loadcapacity lists for different speeds on normal roads and for on track and in mud/sand.

Rule is about, so I figured out:
Mud/sand 50% of pressure for 20kmph( 12.5mph) on road, wich then is max speed to use.
On track,( must be that on gravel), 80% of pressure for 65kmph(35mph) on road.

TMPS sensors are not that good in giving temperature, especialy external sensors, because give pretty acurate the temperature on end of valve, and not of gascompound in the tire.
Beter then is to calculate it back from the pressure change.

For that I made a simple to use list.
Look in that the cold filled pressure at 70degrF( but also can make a list for Celcius and bar or psi), and look behind that for degrF/psi.
Then you can calculate by head acurate enaugh the temp in tire. Or reverse.
If you use it for cold filled at 65 degrF, it wont give dramatic differences.

70degrF./degrF/psi

20 psi/ 15,5F/psi
21 psi/ 15F/psi
22 psi/ 14,5F/psi
23 psi/ 14 F/psi
24 psi/ 13,5F/psi
25 psi/ 13,5F/psi
26 psi/ 13 F/psi
27 psi/ 12,5 F/psi
28 psi/ 12,5 F/psi
29 psi/ 12 F/psi
30 psi/ 12 F/psi
31 psi/ 11,5 F/psi
32 psi/ 11,5 F/psi
33 psi/ 11 F/psi
34 psi/ 11 F/psi
35 psi/ 10,5 F/psi
36 psi/ 10,5 F/psi
37 psi/ 10 F/psi
39 psi/ 10 F/ps
40 psi/ 9,5 F/psi
42 psi/ 9,5 F/psi
43 psi/ 9 F/psi
45 psi/ 9 F/psi
46 psi/ 8,5 F/psi
49 psi/ 8,5 F/psi
50 psi/ 8 F/psi
53 psi/ 8 F/psi
54 psi/ 7,5 F/psi
58 psi/ 7,5 F/psi
59 psi/ 7 F/psi
63 psi/ 7 F/psi
64 psi/ 6,5 F/psi
70 psi/ 6,5 F/psi
71 psi/ 6 F/psi
77 psi/ 6 F/psi
78 psi/ 5,5 F/psi
86 psi/ 5,5 F/psi
87 psi/ 5 F/psi
96 psi/ 5 F/psi
97 psi/ 4,5 F/psi
109 psi/ 4,5 F/psi
110 psi/ 4 F/psi
126 psi/ 4 F/psi
127 psi/ 3,5 F/psi
148 psi/ 3,5 F/psi
149 psi/ 3 F/psi
177 psi/ 3 F/psi

Niw see this is australian forum so list for degrC needed. And read tyre where I wrote tire.

DegrC/psi/psi20C70F/degrF/psi
18,5C/psi/ 1 psi/ 33,5F/psi
17,5C/psi/ 2 psi/ 31,5F/psi
16,5C/psi/ 3 psi/ 30 F/psi
15,5C/psi/ 4 psi/ 28,5F/psi
15 C/psi/ 5 psi/ 27 F/psi
14 C/psi/ 6 psi/ 25,5F/psi
13,5C/psi/ 7 psi/ 24,5F/psi
13 C/psi/ 8 psi/ 23,5F/psi
12,5C/psi/ 9 psi/ 22,5F/psi
12 C/psi/ 10 psi/ 21,5F/psi
11,5C/psi/ 11 psi/ 20,5F/psi
11 C/psi/ 12 psi/ 20 F/psi
10,5C/psi/ 13 psi/ 19 F/psi
10 C/psi/ 14 psi/ 18,5F/psi
10 C/psi/ 15 psi/ 18 F/psi
9,5 C/psi/ 16 psi/ 17,5F/psi
9 C/psi/ 17 psi/ 16,5F/psi
9 C/psi/ 18 psi/ 16 F/psi
8,5 C/psi/ 19 psi/ 15,5F/psi
8,5 C/psi/ 20 psi/ 15,5F/psi
8 C/psi/ 21 psi/ 15 F/psi
8 C/psi/ 22 psi/ 14,5F/psi
8 C/psi/ 23 psi/ 14 F/psi
7,5 C/psi/ 24 psi/ 13,5F/psi
7,5 C/psi/ 25 psi/ 13,5F/psi
7 C/psi/ 26 psi/ 13 F/psi
7 C/psi/ 27 psi/ 12,5F/psi
7 C/psi/ 28 psi/ 12,5F/psi
6,5 C/psi/ 29 psi/ 12 F/psi
6,5 C/psi/ 30 psi/ 12 F/psi
6,5 C/psi/ 31 psi/ 11,5F/psi
6,5 C/psi/ 32 psi/ 11,5F/psi
6 C/psi/ 33 psi/ 11 F/psi
6 C/psi/ 34 psi/ 11 F/psi
6 C/psi/ 35 psi/ 10,5F/psi
6 C/psi/ 36 psi/ 10,5F/psi
5,5 C/psi/ 37 psi/ 10 F/psi
5,5 C/psi/ 38 psi/ 10 F/psi
5,5 C/psi/ 39 psi/ 10 F/psi
5,5 C/psi/ 40 psi/ 9,5 F/psi
5,5 C/psi/ 41 psi/ 9,5 F/psi
5 C/psi/ 42 psi/ 9,5 F/psi
5 C/psi/ 43 psi/ 9 F/psi
5 C/psi/ 44 psi/ 9 F/psi
5 C/psi/ 45 psi/ 9 F/psi
5 C/psi/ 46 psi/ 8,5 F/psi
5 C/psi/ 47 psi/ 8,5 F/psi
4,5 C/psi/ 48 psi/ 8,5 F/psi
4,5 C/psi/ 49 psi/ 8,5 F/psi
⁸4,5 C/psi/ 50 psi/ 8 F/psi
4,5 C/psi/ 53 psi/ 8 F/psi
4,5 C/psi/ 54 psi/ 7,5 F/psi
4 C/psi/ 55 psi/ 7,5 F/psi
4 C/psi/ 58 psi/ 7,5 F/psi
4 C/psi/ 59 psi/ 7 F/psi
4 C/psi/ 63 psi/ 7 F/psi
3,5 C/psi/ 64 psi/ 6,5 F/psi
3,5 C/psi/ 70 psi/ 6,5 F/psi
3,5 C/psi/ 71 psi/ 6 F/psi
3,5 C/psi/ 75 psi/ 6 F/psi
3 C/psi/ 76 psi/ 6 F/psi
3 C/psi/ 77 psi/ 6 F/psi
3 C/psi/ 78 psi/ 5,5 F/psi
3 C/psi/ 86 psi/ 5,5 F/psi
3 C/psi/ 87 psi/ 5 F/psi
3 C/psi/ 91 psi/ 5 F/psi
2,5 C/psi/ 92 psi/ 5 F/psi
2,5 C/psi/ 96 psi/ 5 F/psi
2,5 C/psi/ 97 psi/ 4,5 F/psi
2,5 C/psi/ 109 psi/ 4,5 F/psi
2,5 C/psi/ 110 psi/ 4 F/psi
2,5 C/psi/ 115 psi/ 4 F/psi
2 C/psi/ 116 psi/ 4 F/psi
2 C/psi/ 126 psi/ 4 F/psi
2 C/psi/ 127 psi/ 3,5 F/psi
2 C/psi/ 148 psi/ 3,5 F/psi
2 C/psi/ 149 psi/ 3 F/psi
2 C/psi/ 152 psi/ 3 F/psi
1,5 C/psi/ 153 psi/ 3 F/psi
1,5 C/psi/ 177 psi/ 3 F/psi
1,5 C/psi/ 178 psi/ 2,5 F/psi
1,5 C/psi/ 198 psi/ 2,5 F/psi

Now see this is australian forum so list for degrC needed. And read tyre where I wrote tire. Or do you use Bar?

1,5 bar/ 11,5 C/0,1bar
1,6 bar/ 11 C/0,1bar
1,7 bar/ 11 C/0,1bar
1,8 bar/ 10,5 C/0,1bar
1,9 bar/ 10 C/0,1bar
2,0 bar/ 9,5 C/0,1bar
2,1 bar/ 9,5 C/0,1bar
2,2 bar/ 9 C/0,1bar
2,3 bar/ 9 C/0,1bar
2,4 bar/ 8,5 C/0,1bar
2,5 bar/ 8,5 C/0,1bar
2,6 bar/ 8 C/0,1bar
2,7 bar/ 8 C/0,1bar
2,8 bar/ 7,5 C/0,1bar
3,0 bar/ 7,5 C/0,1bar
3,1 bar/ 7 C/0,1bar
3,3 bar/ 7 C/0,1bar
3,4 bar/ 6,5 C/0,1bar
3,6 bar/ 6,5 C/0,1bar
3,7 bar/ 6 C/0,1bar
4,0 bar/ 6 C/0,1bar
4,1 bar/ 5,5 C/0,1bar
4,5 bar/ 5,5 C/0,1bar
4,6 bar/ 5 C/0,1bar
5,1 bar/ 5 C/0,1bar
5,2 bar/ 4,5 C/0,1bar
5,8 bar/ 4,5 C/0,1bar
5,9 bar/ 4 C/0,1bar
6,8 bar/ 4 C/0,1bar
6,9 bar/ 3,5 C/0,1bar
8,0 bar/ 3,5 C/0,1bar
8,1 bar/ 3 C/0,1bar
9,6 bar/ 3 C/0,1bar
9,7 bar/ 2,5 C/0,1bar
12,0 bar/ 2,5 C/0,1bar

Psi here.

What does the tyre placard on the car door say? It seems nobody thinks that Land Rover know what is best for their own products.
something like 33 front and 38 rear on low profile tyres.
235 85 r16 tyres have far more internal air volume than the licorice stick low profile tyres so should probably have lower pressures than stock.

You are just punishing the car suspension and yourself by running excessive pressures and risk what is in this quote. Tyres are a part of the suspension.

I have not long owned my P38 and took it for MOT yesterday. Everything was fine apart from needing 2 rear tyres. They had previously had too much pressure in as the sides have no wear but the centres are illegal.

The wheels on it don't look like the originals, and the tyres are 255 / 55 / R19.

I have trawled the net trying to find the correct pressures, but everyone seems to be running them differently.

Currently have 27 in the fronts which are fine, and 37 in the rears. Before I go and put 2 new rear tyres on I would like to know what the recommended pressures are

I run pretty stock cold pressures even in 40C temperatures as the temps raise the internal pressure anyway. About 30 front and 42 rear and 45 rear towing in my D2 TD5 . Tyres are Bridgestone 245 70r16 AT.
Regards PhilipA

Originally Posted by PhilipA

What does the tyre placard on the car door say? It seems nobody thinks that Land Rover know what is best for their own products.
something like 33 front and 38 rear on low profile tyres.
235 85 r16 tyres have far more internal air volume than the licorice stick low profile tyres so should probably have lower pressures than stock.

You are just punishing the car suspension and yourself by running excessive pressures and risk what is in this quote. Tyres are a part of the suspension.



I run pretty stock cold pressures even in 40C temperatures as the temps raise the internal pressure anyway. About 30 front and 42 rear and 45 rear towing in my D2 TD5 . Tyres are Bridgestone 245 70r16 AT.
Regards PhilipA

I think the problem, especially with tyre advice is that everyone has different tyres with different constructions and with different priorities with the tyres - and short of having OE tyres with no thought about tyres (like 99% of people) then the placard may not suit. You can see that in the post where factory tyre pressure recommendations varied over time, and I would assume that is because the tyre fitted varied.

Airing down offroad, my tyres all go down to different pressures. Simex on sand might be 10.5psi, GoodYear MTR 12 psi and Pirelli ATR 15psi. Measure the foot print length to get your pressure and when loaded it will probably be different from front to back.

On road my old Cooper ST needed to be run at a minimum of 35-36psi as the carcass was so unstable, but the STT could be run at 32. The GoodYear MTR needs to be run at 32 as over that the carcass stiffness gets too much but it is stable even at 28. The Pirelli ATR can be run anywhere from 30 - 40 and its fine (under that just understeers a bit, and this I think is why LR have low front pressures - to induce stability).

You can see the variation and thats why the factory pressures sometimes need to be varied from. I actually think the factory settings generally are set for max comfort with a stable rear end and leading to understeer when pushed with the OE tyre - but vary the carcass and the pressures will change.

On my Audi which has 21" rims and low profile tyres, the pressures are set to give even wear and to protect the shoulders, these tyres are really sensitive to pressure and get run above placarded tyre pressures otherwise they get chewed out, and at $500-600 tyre, I don't want them chewed out.