I was advised early on in my motorhome ownership that there’s 3 things I need to keep an eye on… 1 – The condition of the fresh water tank. 2 – My leisure battery. 3 – My tyres. (for most motorhomers there may be a 4th which is the wine stock!)

When we collected our current Frankia motorhome the ride was very stiff and you could feel every bump of the road. Alko chassis’s are known for a rough ride but after some research some people said they were able to relieve some of the hardness by adjusting the tyre pressure.

What is the correct tyre pressure?

Most motorhomes or campervans have a sticker inside the door stating the recommended tyre pressures but this is missing on ours.

Upon collection, all four tyres were inflated to just under 80psi (5.5bar). As an experiment I dropped the pressure down to 65psi (4.5bar) which did make the ride slightly softer. However I was concerned that the tyres were under inflated. I emailed the tyre manufacturers with the tyre type, model, type of vehicle, position of tyre, and the axle weight which was taken from when we had the van weighed. You could also find the axle weights on the VIN plate in the engine bay or door pilar but this is the maximum weights so unless you go to a weighbridge and obtain accurate fully loaded weights this is the next best figure. Both manufacturers came back to me within 48 hours with the recommended tyre pressures:

TOYO H09 215/70R15C on the rear with axle weight of 1561Kg: recommended to 50psi (3.4bar)

Michelin Agilis Camping on the front with axle weight of 1646kg: recommended to 55psi (3.8bar)

Both were even lower than I had experimented with.

I understand that the proper camper tyres such as the ones on our front have stiffer side walls and thus can affect ride quality.

There is lots more info on the www.tyresafe.org web site and this PDF leaflet specifically targeted at motorhomes is very informative.

If you need to convert PSI to Bar and other measurement values, see the chart below.

psi kg/cm² bar kPa psi kg/cm² bar kPa psi kg/cm² bar kPa
5 0.4 0.3 34 41 2.9 2.8 283 77 5.4 5.3 531
6 0.4 0.4 41 42 3.0 2.9 290 78 5.5 5.4 538
7 0.5 0.5 48 43 3.0 3.0 296 79 5.6 5.4 545
8 0.6 0.6 55 44 3.1 3.0 303 80 5.6 5.5 552
9 0.6 0.6 62 45 3.2 3.1 310 81 5.7 5.6 558
10 0.7 0.7 69 46 3.2 3.2 317 82 5.8 5.7 565
11 0.8 0.8 76 47 3.3 3.2 324 83 5.8 5.7 572
12 0.8 0.8 83 48 3.4 3.3 331 84 5.9 5.8 579
13 0.9 0.9 90 49 3.4 3.4 338 85 6.0 5.9 586
14 1.0 1.0 97 50 3.5 3.4 345 86 6.0 5.9 593
15 1.1 1.0 103 51 3.6 3.5 352 87 6.1 6.0 600
16 1.1 1.1 110 52 3.7 3.6 359 88 6.2 6.1 607
17 1.2 1.2 117 53 3.7 3.7 365 89 6.3 6.1 614
18 1.3 1.2 124 54 3.8 3.7 372 90 6.3 6.2 621
19 1.3 1.3 131 55 3.9 3.8 379 91 6.4 6.3 627
20 1.4 1.4 138 56 3.9 3.9 386 92 6.5 6.3 634
21 1.5 1.4 145 57 4.0 3.9 393 93 6.5 6.4 641
22 1.5 1.5 152 58 4.1 4.0 400 94 6.6 6.5 648
23 1.6 1.6 159 59 4.1 4.1 407 95 6.7 6.6 655
24 1.7 1.7 165 60 4.2 4.1 414 96 6.7 6.6 662
25 1.8 1.7 172 61 4.3 4.2 421 97 6.8 6.7 669
26 1.8 1.8 179 62 4.4 4.3 427 98 6.9 6.8 676
27 1.9 1.9 186 63 4.4 4.3 434 99 7.0 6.8 683
28 2.0 1.9 193 64 4.5 4.4 441 100 7.0 6.9 689
29 2.0 2.0 200 65 4.6 4.5 448 101 7.1 7.0 696
30 2.1 2.1 207 66 4.6 4.6 455 102 7.2 7.0 703
31 2.2 2.1 214 67 4.7 4.6 462 103 7.2 7.1 710
32 2.2 2.2 221 68 4.8 4.7 469 104 7.3 7.2 717
33 2.3 2.3 228 69 4.9 4.8 476 105 7.4 7.2 724
34 2.4 2.3 234 70 4.9 4.8 483 106 7.5 7.3 731
35 2.5 2.4 241 71 5.0 4.9 490 107 7.5 7.4 738
36 2.5 2.5 248 72 5.1 5.0 496 108 7.6 7.4 745
37 2.6 2.6 255 73 5.1 5.0 503 109 7.7 7.5 752
38 2.7 2.6 262 74 5.2 5.1 510 110 7.7 7.6 758
39 2.7 2.7 269 75 5.3 5.2 517 111 7.8 7.7 765
40 2.8 2.8 276 76 5.3 5.2 524 112 7.9 7.7 772

psi = pounds per square inch
kg/cm² = kilogram force per square centimetre
bar = err, well a bar (1 bar is about the same as normal atmospheric pressure at sea level)
kPa = kilopascal

Tyre pressures can change with temperature so if your tyres are hot then the pressure will read slightly higher.