What tyres on your van

[Guest 1footinthegrave]

All extremely interesting, thanks Derek, but still looking for the seemingly impossible, an accurate tyre gauge, any recommendations please from folk out there.

[Derek Uzzell]

1footinthegrave - 2012-03-06 9:47 AM

 

All extremely interesting, thanks Derek, but still looking for the seemingly impossible, an accurate tyre gauge, any recommendations please from folk out there.

 

Easily answered - this one:

 

http://tinyurl.com/7l994b5

 

This is a USA-manufactured gauge and, with a 0-100psi range, it should be suitable for motorhomes.

 

It was the most accurate of a number of tyre pressure gauges tested by Motorcycle News in 2008. See:

 

http://tinyurl.com/7wtyaf4

 

(Of course, if you want a super-accurate gauge at a super-cheap price, that's another matter!)

 

 

[OxfordMorgan]

Derek Uzzell - 2012-03-06 9:38 AM

 

For their 'ordinary' light-commercial vehicle 215/70 R15C 109/107R Agilis 81 tyre Michelin provides the following axle-load/inflation-pressure data:

 

Axle-load Inflation-pressure

 

2060kg ......... 65psi

1660kg ......... 51psi

1460kg ......... 43psi

 

These data (as one would expect) near-enough match the Continental data provided by Robin Hood.

 

These are 'static load' pressure recommendations and Michelin have advised in the past that the front-axle static-load inflation pressure may be increased by 10% to deal better with cornering and braking weight transference. For example, for a measured FRONT-AXLE load of 1660kg, Michelin would suggest around 56psi (51psi + 10%).

 

Playing about with tyre pressures must be based on accurate AXLE-LOAD measurements. There's little point weighing the complete vehicle then guessing at its axle-loadings. It's also worth pointing out that tyre manufacturers' pressure recommendations are based on a relatively warm ambient temperature (I've been told that 20°C is the norm) - so it's a waste of time with motorhomes to seek accuracy down to a single-figure psi.

 

It's also worth emphasising that some vehicles do have a harder ride than others even when their tyres are identical and run at identical pressures. If it turns out that, when tyre-pressures are matched to measured axle-loads, the vehicle still has a harsh ride, then that's just tough luck. What should never be done is to reduce tyre pressures below their axle-load recommendation in the hope that this will soften a harsh ride. Tyres being run at unsuitably low pressures are potentially lethal, while a harsh ride is just uncomfortable.

 

All,

 

To add to this, I would recommend emailing the manufacturer to request its recommended pressures with your current vehicle weight

 

I have just put Agilis Camping tyres on my Autocruise (4150KG) and got a good reply.. See email train below..

 

I wanted to know specifically about the Camping Tyre version of the Agilis

----

 

Dear Morgan

 

Thank you for your enquiry about tyre pressures for your motorhome.

 

The suggested tyre pressure for the rear of a motorhome running on the Agilis Camping is 80psi (single rear axle) 69psi (twinned rear axle). This is due to the construction of the tyre with 2 casing plies enabling the use of higher pressures. Its construction and the use of higher pressures is designed to cope with continual heavy loads sometimes found on Motorhomes and can help with wear pattern issues if lower pressures are used particularly on the rear axle.

 

The front pressures however can be adjusted according to accurately weighed axle loads for a more comfortable ride and optimum performance.

 

Taking the current rear weight away from the current gross vehicle weight gives a front axle weight of 1750kg. Our suggested pressure for the front tyres is therefore 55psi

 

Should you require any further assistance please contact us on 0845 366 1590 (UK & NI) or 0044 (0) 1782 401590 (ROI), quoting the reference number above.

[Derek Uzzell]

As many forum members will be aware, the snag with seeking tyre-pressure advice from Michelin nowadays regarding their "Agilis Camping" camping-car tyre is that you'll get told "Use 80psi for the rear-axle", irrespective of any measured rear-axle loading that you provide. This is a somewhat peculiar philosophy, but Michelin believe that some higher power (presumably ETRTO) compels them to do this.

 

Continental, on the other hand, if asked for inflation-pressure advice for their "VancoCamper" camping-car tyre, will provide a rear-axle pressure recommendation that reflects the measured rear-axle loading.

 

[Robinhood]

....indeed; As i posted above, Michelin have become somewhat more cagey about tyre advice.

 

Odd, really, since I've twice in the past had them recommend 64psi for 16" Camping tyres at the old Maxi maximum rear axle weight of 2120kg. (the front recommendations were in line with the uplift described by Derek previously).

 

I can vouch for the fact that, in my case, both the handling and ride were improved dramatically by dropping the pressures from the previous 80psi.

[snowie]

Robinhood - 2012-03-06 8:18 AM

 

 

 

Bearing in mind Ducato front max load = 1850Kg, current load 1520Kg and rear max load =2000Kg, current load = 1440Kg, there would appear to be scope for a proportional reduction to front and rear.

 

I'll keep researching.

regards

alan b

 

 

The best solution is still advice from the manufacturer.

 

 

Hi Robin. I thought I'd update this thread; it's given me plenty of food for thought; I've been running my tyres way too high, so I'll be dropping them to 46psi front and 44psi rear to account for all up load when we depart for our first trip on Monday. Then I'll experiment around the table provided.

 

Thanks to all for input

 

alan b

 

I have a detailed reply from Bridgestone:

Hello Mr Bell

The variance as per axle load is as follows.

 

Tyre Pressure (psi)              36           40           44          48          51

215/70R15C – 109/107 – 745kg    804kg    873kg    930kg   975kg (tyre capable, but not recommended)

 

So at 1520kg (760 per tyre) and 1440kg (720 per tyre) respectively, you should be running at 40psi front, and 36psi rear.

And adjust as per limit, per tyre load.

 

Kind regards

 

Paul Reilly

Casings Management - Technical Department

Bridgestone UK Ltd

 

 

 

[snowie]

Robinhood - 2012-03-06 8:18 AM

 

 

 

Bearing in mind Ducato front max load = 1850Kg, current load 1520Kg and rear max load =2000Kg, current load = 1440Kg, there would appear to be scope for a proportional reduction to front and rear.

 

I'll keep researching.

regards

alan b

 

 

The best solution is still advice from the manufacturer.

 

 

Hi Robin. I thought I'd update this thread; it's given me plenty of food for thought; I've been running my tyres way too high, so I'll be dropping them to 46psi front and 44psi rear to account for all up load when we depart for our first trip on Monday. Then I'll experiment around the table provided.

 

Thanks to all for input

 

alan b

 

I have a detailed reply from Bridgestone:

Hello Mr Bell

The variance as per axle load is as follows.

 

Tyre Pressure (psi)              36           40           44          48          51

215/70R15C – 109/107 – 745kg    804kg    873kg    930kg   975kg (tyre capable, but not recommended)

 

So at 1520kg (760 per tyre) and 1440kg (720 per tyre) respectively, you should be running at 40psi front, and 36psi rear.

And adjust as per limit, per tyre load.

 

Kind regards

 

Paul Reilly

Casings Management - Technical Department

Bridgestone UK Ltd

 

 

 

[Robinhood]

.....the Bridgestone pressures look a bit low to me, and the load index of 109 means they should take loads of up to 1030kg (the implicit 975kg limit quoted is for a load index of 107, and a 109/107 load index means 109 when used in "single wheel" configuration, whereas the 107 applies to a twin rear wheel).

 

Nonetheless, they should be the experts, and the information supplied is clear - print it off and keep a copy in your glovebox.

 

If it were me, however, I'd stick closer to the pressures which arise from both myself's and Derek's data, for both Continental and Michelin tyres, as IMO, these appear to be closer to the industry norms. Your chosen starting point isn't far off these (albeit without the additional load allowed for).

 

Whatever, I'll be surprised if the ride and handling don't improve a bit. ;-)

[colin]

Robinhood - 2012-03-09 1:32 PM

 

.....the Bridgestone pressures look a bit low to me, and the load index of 109 means they should take loads of up to 1030kg (the implicit 975kg limit quoted is for a load index of 107, and a 109/107 load index means 109 when used in "single wheel" configuration, whereas the 107 applies to a twin rear wheel).

 

 

That is because they have been given incorrect data, they would never have given these pressures if they had been told the correct max loads

[Keithl]

snowie - 2012-03-05 11:05 PM

 

4.1 approx= 60psi, 4.5 approx= 65psi

 

So dropping 5psi front and rear could be beneficial

 

Bearing in mind Ducato front max load = 1850Kg, current load 1520Kg and rear max load =2000Kg, current load = 1440Kg, there would appear to be scope for a proportional reduction to front and rear.

 

I'll keep researching.

regards

alan b

 

Alan,

 

You appear to have given Bridgestone the loads at a semi-unladen condition and not the true loads you will be running at.

I suggest you fully load your MH then get it re-weighed and calculate the correct pressures now you have a sliding scale.

Under inflation can be worse than over inflation so be warned.

 

Keith.

 

Edit. Post crossed with Colin's 'cos the batteries went flat in my keyboard :-(

[Robinhood]

colin - 2012-03-09 1:41 PM

 

Robinhood - 2012-03-09 1:32 PM

 

.....the Bridgestone pressures look a bit low to me, and the load index of 109 means they should take loads of up to 1030kg (the implicit 975kg limit quoted is for a load index of 107, and a 109/107 load index means 109 when used in "single wheel" configuration, whereas the 107 applies to a twin rear wheel).

 

 

That is because they have been given incorrect data, they would never have given these pressures if they had been told the correct max loads

 

 

.....I don't quite follow that argument.

 

They've quoted pressures at various given loadings - my concern is that these appear somewhat low to me at the associated loadings quoted (when compared to other manufacturers).

 

I agree that the OP hasn't requested pressures for the ACTUAL axle loadings (and should, of course, run at pressures that are appropriate to those), but neither is he proposing running at the pressures quoted for the semi-loaded state.

 

Whilst I would still suggest that a return to a weighbridge in a fully-loaded state, and then extrapolate from the given pressures, would be better, I suspect that his quoted "trial" figures of 46/44 will be somewhat better than the pre-existing pressures, and not over-far off the mark (against the Bridgestone table).

 

 

[snowie]

Hi Keith;

You are correct to suggest that I should get the van weighed again and use the pressures given to adjust based on that.

 

Our trip next week will be a semi-laden situation, no bikes or bike rack, no bbq, minimal onboard water, all pretty streamlined.

 

I have weighed almost everything and have it on a spreadsheet, but not looking to get too a-r about it.

 

My priority is safety over comfort, so at this point I may well adjust the pressures to halfway between the max and the pressures I quoted earlier. Just glad to have some data on which to base judgements,

 

regards

alan b

[snowie]

HOLD THAT POST!!!

 

Bridgestone have come back to say tht last information was wrong!!

The correct pressure should be 58Psi; which is not much of an improvement.

 

Looks a bit as though the quality control department checked the advice being given!!

 

I shall be out there reinflating later today or Sunday at the latest

 

I shall consult the information that you guys have posted; (on my head; I know)

 

thanks again

alan b

 

 

 

[Robinhood]

snowie - 2012-03-09 5:16 PM

 

HOLD THAT POST!!!

 

Bridgestone have come back to say tht last information was wrong!!

The correct pressure should be 58Psi; which is not much of an improvement.

 

Looks a bit as though the quality control department checked the advice being given!!

 

I shall be out there reinflating later today or Sunday at the latest

 

I shall consult the information that you guys have posted; (on my head; I know)

 

thanks again

alan b

 

 

 

.....well, I feel at least in part vindicated. ;-)

 

....but I don't like that figure, either. :-S

 

As on the other thread running, I've pulled a set of 2011/12 data for Continental tyres, and this agrees with my somewhat older set already posted.

 

Derek's data for Michelin is within a gnat's whisker of this.

 

I wouldn't expect much (if any) variation between manufacturers for tyres of similar profile, reinforcement and load index.

 

The Continental data (for 215/70R15C 8PR 109/107) is:

 

bar axle load (kg)

 

3.0 1490

3.25 1590

3.50 1685

3.75 1780

4.0 1875

4.25 1970

4.5 2060

 

...I provide this for reference only, not as any recommendation.

 

;-)

[colin]

snowie - 2012-03-09 5:16 PM

 

HOLD THAT POST!!!

 

Bridgestone have come back to say tht last information was wrong!!

The correct pressure should be 58Psi; which is not much of an improvement.

 

Looks a bit as though the quality control department checked the advice being given!!

 

I shall be out there reinflating later today or Sunday at the latest

 

I shall consult the information that you guys have posted; (on my head; I know)

 

thanks again

alan b

 

 

 

58psi sounds a good starting point, see how you get on, then when convient load up with absolutly everthing you could ever reasonably expect to carry including passengers, get weighed then consider what else you might load such as a few crates of wine or whatever and access pressures then. As you say best be on safe side, having a tyre blow on a heavily leaden van is not nice, believe me ;-)

[snowie]

An update;

Just got back from the first trip of the year; Crystal Palace CC site for access to Central London (David Hockney; v-crowded but good; and Don McCullin; also very good. London Eye; a bit disappointing really, but london was very enjoyable) A bus pass is great value! and being above ground much nicer than the Tube.

 

After 3 nights in Crystal Palace we drove up to Hope, in the Peak District. Very beautiful, and the start of a long relationship with the Peak District I hope.

 

I set the tyre pressures at 57Psi for this trip, and was pleased with the performance. Not sure I'd want to go much lower but will experiment a little.

Still waiting for detailed load tables from Bridgestone, after earlier wrong information.

 

Regards,

alan b