Trailer tyres

[Rapier]

I recently bought a combi trailer for the latest boat. At a guess, I'd say it weighs in at about 100 kgs bare at the most. The 4ply tyres had cracked sidewalls, so replaced them with 6plys (400x8). The tyres have a max load of 335kgs at 5 bar. My trip yesterday was most unpleasant, in that any speed over 50 mph meant my teeth chattering with the vibrations setup.

We discovered that most of the grease had escaped from the hardened seal at the back of the, albeit slightly rumbly bearing, as I'd probably not tightened that nut properly before backing it off. Classic fever was kind enough to help with new bearings, water bouy with grease, but on the return home, it seemed to make little difference.

If I have a load less than the 335kg per side, say overall boat and trailer load at 180kgs, surely 75psi is way too much tyre pressure? The original 4plys were at about 28psi each.These are such dinky tyres with little load that I would think 40psi would be plenty, with 50psi if towing a GRP sailing dingy with greater weight? I plan to test en-route to my local indespension lot tomorrow, but any knowledge would be helpful.

[Alacrity]

I think I would be looking at 30-35psi with that little load on them. I would be interested to hear what others have to say.

[VivaSportiva]

I agree as I run my tyres on the Glen L which has 250kg units at 30 psi without any bounce or vibration at all. When I do stop I always check the tyres and bearings for heat as with any of my trailers but so far no problems. The tyre pressure of between 30 and 35psi sounds right to me.

[Woodwych]

I bought a new trailer from SBS last year for Woodwych. Their service manual just has a table under the 'tyre pressure ' section listing tyre sizes and PSI guidance. For a 400x8 4ply it says max PSI of 60 "at max load , to be used as guideline only"

I rang them to try and get some guidance on what do do at less than "max load" as i'm in the same boat (!) having a very light load. They wouldn't commit to a reading but just said to drive a bit and check for heat...

[haventaclue]

35PSI is more than enough for that light a load.If more than 35, that'll account for the bounce and vibration.Think on it like a football,the more air,the harder it is and the higher it'll bounce if the load is not there to keep it down. I tow "NO-KIT" on a single axle Snipe,break back trailer on 40PSI,and sometimes I think that is too much.A couple of hundred miles,no over heating and a very comfortable run.I would guess boat and trailer at about 300+kgs

[Rapier]

Thanks for the replies, think I'll let another 5psi out to 35psi and see how it goes.

On another related subject, am doing a lot of towing this summer with my other boat & having had a delamination on a 500x10 tyre a few years back,(mostly likely due to high load, 12 hour non-stop constant high temperature towing) I think I'd prefer to go with proper road/car tyres, a to spread the load better and b. get greater longevity (perhaps). I think alacrity did the switch, but has anyone else gone down this route? Are there other benefits. Trailer is a de Graaf, 600kg limit.

[Alacrity]

I used to use the same Towsure wheel & tyre combo that I believe you have been using under Tango etc. & found the tyres wore out rapidly & I also had one set de-laminate. I believe either car or 'proper' trailer tyres bought through a reputable tyre dealer represent better value for money long term, not to mention peace of mind.

Be careful to get the correct loading for the weight the tyre will be carrying - bearing in mind that boats make very good trailers so tend to get a lot of stuff packing in them if you are going away for a spell with it. I Myself had a tyre issue (blow out) & found the weight on each tyre was over the max limit without any fuel or kit in the boat.

**EDIT** Apologies to Towsure it wasn't the Towsure tyres that de-laminated - although they did wear out very quickly - but the tyres supplied on my De-Graaff trailer under my Broom which was bought new. I have just found this comment I made on a thread from 2012:

I had exactly the same happen with exactly the same trailer make & model. We bought them at the same time about 4-5 years ago & both my tyres delaminated in 2009. I must confess to having run with low tyre pressures at one time, purely through my own lazyness so that may have been the reason in my case (I'm not suggesting for one moment Nick did this), but its as Al says, its wise to keep a careful eye on the tyres as most are not known makes - which of course doesn't automatically mean they are bad.

[petrolhead]

Yes, my 8inch and metric similar size tyres I run way under the pressure quoted on them, the difficulty is max load can only be carried at max pressure and that is the only rating you get! If pressure is reduced the max load also goes down but nobody can help by how much.
I have the same issue on a 4 wheel car trailer, with a car on it needs lots of pressure, with nothing on it bounces horribly and I reduce them to typical car pressures of 30-35psi.
Heat is what to watch for as mentioned already or bad feathering on outside edges if run too flat.

[floater]

Resurrecting as old post here, but I have been looking around the interweb in search of guidance regarding tyre pressures and loading having just upgraded the tyres on my trailer following a blowout. I found this which seems feasible http://caravanchronicles.com/guides/cal ... r-caravan/