winchcombe 4250k tyre pressures

Does anyone know the tyre ratings and tyre pressures for the newer winchcombe which has been updated to 4250k now ?

road warrior wrote:Does anyone know the tyre ratings and tyre pressures for the newer winchcombe which has been updated to 4250k now ?

Not sure but there are pressure calculators online for tyre size/ratings v vehicle weight which should give you a good indication.
BTW, have you changed the weight from 3850 to 4250 and can you tell me what was involved?
Thanks

Yes I have upweighted with rear airbags, but there are other things that have to be of spec or it can't be done, such as tyres that have to be 115r minimum and wheels that also have to be capable of carrying the extra weight. I am also finding the extra weight is testing the brakes badly, as the sprinter also suffers  from spongy brakes,  so I will be upgrading the brake disks and pads to drilled and grooved on my return as I experienced brake fade on a mountain road last week. Ironically the overheating must have burned some crap off and they are now a bit better !
To return to my question I want to know the spec of the wheels the spec of the tyres and the air pressure in the tyres applicable to a 4250k motorhome.

The latest Winchcombe from AS is 4100kg MPTLM, not 4250kg.
 Presumably you have uprated from 3880kg?

The Sprinter manual (pg 294 circa) gives required pressure for various tyre sizes/load ratings for 6.5Jx 16 ET62 wheel size which the WInchcombe would originally been fitted.

If you know your revised loaded axel weights you can look it up there. Max front axel is 2000kg, rear is 2430kg.

Thanks Peter,  it says 71psi for 2430k,  it also says I'm speed restricted to 90km/h on my 235 65 16 tyres, which isn't very good. Given that it no doubt factory fitted c type commercial tyres or perhaps wrote the spec based on the likelihood of c tyres I wonder how CP tyres might affect that spec ?
Or maybe it's based on 115/113r spec. While I'm here, what on earth is 115/113r supposed to mean. I have read that my tyre being a CP is just 115r. Even so it only JUST reaches the 4230k spec, and I am wondering whether it might be prudent to move to 225/75/16 116r as that says 67psi and 140 km/h, while I have no intention of going anywhere near 140 km/h, the extra comfort margin is attractive.

235/65 16 C 121N(118R) tyres don't have that restriction. (Not a low chassis vehicle)

I have these on my Gloucester (Malvern) similar to Winchcombe.

Those sound more the ticket, are they CP ?

road warrior wrote:Those sound more the ticket, are they CP ?

No, 4 Season Continentals, as originally specified request by AS on original build sheet. Winchcombe probably the same.

The current Winchcombe appears to have a MTPLM of 4100 kg not 4250 kg or 3850 kg.  With a 4100 kg MTPLM the rear axle MAM is shown as 2430 kg.  

If the rear axle is evenly loaded, which it wont be, that gives 1215 kg on each wheel/tyre.  That would require the load index to be at least 115.  However, tyre manufacturers recommend the load index should be for an axle mass that is 10% higher, due in part to uneven loading across the axle, which suggests 118.  

The only R16 tyre I can see with a load index of 118 is the 225/75 R16 which comes as a C or CP.  CP tyres are recommended for coachbuilt motorhomes.  

A 10-ply 235/65 R16 with a much higher load index of 121 could also be fitted.  This is a C tyre (there is no CP variant) with a maximum permitted pressure of 83psi at its maximum load.  TyreSafe's online calculator recommends 75 psi for the rear tyres if the rear axle load is only 2430 kg.  A lower pressure is recommended for the front tyres which depends on the actual front axle mass.

I suggest you contact A-S or an A-S dealer to find out what tyres are fitted to the current Winchcombe.