Any tyre boffins out there

Discussion in 'Motorhome Chat' started by buttons, Mar 22, 2010.

  1. buttons

    buttons Funster

    Aug 27, 2009
    I have just replaced my rear tyres with 8ply not 6ply like the ones they were replacing. Not a problem I thought. Stronger proper commercial tyres that were recommended by the local tyre outlet so I went for them.
    I’ve had them for a couple of weeks now with a few different pressures 54-50 and now 48psi. My problem is that I appear to be getting a rougher ride. I can hear things that I didn’t hear before like cutlery and saucepans and it starting to irritate me a lot.
    Is this my imagination or are 8ply tyres best restricted to commercial users where ride quality is less important. it's that bad I'm thinking of changing them again.:cry:
    Edit.. One other small point I had to brake hard for a pheasant yesterday, it was damp and possibly a bit slippery but the rear wheels locked, not a problem but in three years that was the first time. Possibly a coincidence.
    Last edited: Mar 22, 2010
  2. gazz

    gazz Formerly "gazznhelz"

    Mar 16, 2010
    Eastwood, Notts
    8 ply will be stiffer, especialy the side walls, which is handy for commercials, but not for light weight motorhomes.

    my van i have to use 8 ply tyres because it's a 4.5 tonner, i get a bit of a rough ride, but i'm used to it, i just made up holders for plates and glasses to stop them ratteling.
  3. Snowbird

    Snowbird Funster Life Member

    Apr 24, 2009
    I think more depends on the tread patern than the ply rating.
    I know the diference that road tyres make on my 4x4 as opposed to off road or M&S tyres.
    If the new tyres are of the knobly tread patern,mabe thats the problem.
  4. lebesset


    May 31, 2009
    for a start the tyres won't have either 6 plies or 8 plies ; they may have the old fashioned ply RATING marking , which was the number of cotton plies that their strength it is equivilent to

    the current system is of course load index , which tells you the maximum load the tyre can carry in single or dual formation [ dual isn't double the single ]

    so as you have a stronger tyre it won't need the same inflation pressure
    so get the axle weighed when fully laden , then refer to the ETRTO charts for the correct pressure to carry that load for that tyre ; if you can't find that any tyre manufacturer has a copy , but I think it is all still on the toyo website
    personally I just cross reference the load index with the load to get the pressure
    and also I just fit the correct tyre as laid down by the vehicle manufacturer ....they spend a lot of time and effort to work out the best fitment

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