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KC Saayman
Frequent User
Username: kc_saayman

Post Number: 11
Registered: 10-2004
Posted on Wednesday, 10 November, 2004 - 10:44 pm:   Edit PostDelete PostView Post/Check IP

Can anyone perhaps tell me what the diameter is of the original 8.20 X 15 tyre as fitted to Silver Cloud’s? I am trying to find out what the correct size in radial tyres should be, and want to keep the ride height as close to original as possible.

Thanks

KC
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Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 425
Registered: 4-2003
Posted on Thursday, 11 November, 2004 - 01:04 am:   Edit PostDelete PostView Post/Check IP

I found the chart below some time ago under:

http://www.northhantstyre.co.uk/fqa%20tyre01.htm

Somehow I don't trust it, as it cross references an 820x15 with a 900x15, and also with 235x15 and 235.75x15.

My understanding is that the Cloud tyres were originally 100% aspect ratio, giving an overall diameter of 31.4". A 235x15 (=235.80x15) has a height of 30", a 235.75x15 is 29". A Shadow 235.70x15 is 28" in diameter.

In any case, most Clouds can handle a 235.70x15 Shadow tyre. There's not much else around which fits I believe.



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KC Saayman
Frequent User
Username: kc_saayman

Post Number: 12
Registered: 10-2004
Posted on Thursday, 11 November, 2004 - 03:43 pm:   Edit PostDelete PostView Post/Check IP

Hi Richard

Thank you very much for this information. I did not realise that the Cloud wheels are so much taller than the Dawn / Mk VI, even though the latter has 16” rims as opposed to the Cloud’s 15”. The Mk VI wheels are 29” high.

It sounds like 235 / 80 X 15 is the best option, but are they not too wide? I am worried that the tyres will rub on full steering lock. The 235 / 70 or 75’s will change the appearance too much, as they are so much smaller than the originals.

By the way, this research is on behalf of a friend who wants to go for radials following my experience with my Mk VI. My car has been totally transformed!

Regards
KC
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Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 426
Registered: 4-2003
Posted on Friday, 12 November, 2004 - 03:51 am:   Edit PostDelete PostView Post/Check IP

KC, Sorry !

I take it all back. According to this site, 820x15 tyres are around 29.5" diameter:

https://www.universaltire.com/Default.asp

Select Tire Search and enter 820-15

DUNLOP FORT WH4 BLACK
Size - 820H15
Construction: 6 ply rated nylon
Overall Diameter: 29.25
Tread Width: 6.00
Load Capacity: 1700 @ 35 psi


FIRESTONE 3 1/2 INCH WHITEWALL
Size - 820-15
Construction: 4 ply polyester
Overall Diameter: 29.56
Cross Section: 8.35
Tread Width: 5.00
Tubeless
Load Capacity: 1920 @ 32 psi
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KC Saayman
Frequent User
Username: kc_saayman

Post Number: 13
Registered: 10-2004
Posted on Friday, 12 November, 2004 - 01:24 pm:   Edit PostDelete PostView Post/Check IP

Hi Richard

This is good news, as there are two suitable tyres available locally (South Africa)

Michelin LTX MMS 235 / 75 15. Measures 28.8”

If that is too wide there is a Michelin Synchrone 215 / 80 15 which measures 28.5”.

Both these tyres are nearly as tall as your revised figures.

Thanks for the input!

Regards

KC
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Peter Colwell
Experienced User
Username: peter_colwell

Post Number: 15
Registered: 3-2005
Posted on Wednesday, 07 June, 2006 - 07:35 am:   Edit PostDelete PostView Post/Check IP

When I bought my Silver Cloud 1 a few months ago, it was fitted with old cross plies and desperately needed new tyres.

To make a long story short, I ended up with Mastercraft (Cooper) Sensys, 235/70/15 with narrow white wall.

I have to say that the news is all good. They look perfect on the car, both from side and head on. Directional stability is very good, with no tendency to wander at all. Ride is smooth and quiet. I have not precisely checked the speedo accuracy, but there is certainly no major problem in that area.

I had found the discussion on sizes and appearance somewhat confusing, and I have seen some cars with truck type tyres that look very ungainly.

Peter

Silver Cloud tyres
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William Payne
Unregistered guest
Posted From: cpe-071-075-085-026.carolina.res.rr.com
Posted on Sunday, 28 January, 2007 - 01:44 am:   Edit PostDelete PostView Post/Check IP

Just purchased a LHD 60 RR which has been in storage since 1982. The original tyres are still on the car--885-900x15. If memory serves, there was an effort by manufacturers to limit tire sizes and they began combining sizes to reduce inventory spread.

On another note, Michelin tyres tend to be very unforgiving when driven near or at the limit. Primarily they give no warning to the driver that the limit of adhesion is approaching. The result typically was a dramatic loss of control. Given the nature of the cars, probably not an issue for most Rolls drivers.





(Message approved by david_gore)
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Jeff Jones
Experienced User
Username: jeffoir

Post Number: 24
Registered: 5-2007
Posted on Sunday, 06 April, 2008 - 02:55 pm:   Edit PostDelete PostView Post/Check IP

Hi All,

I'm getting new tyres for my Cloud and have decided on radials- so I thought I would revive this thread in the hope of getting a few questions answered.

1. The closest tyre diameters to the original 8.20x15's I can find (designed for passenger cars as opposed to light trucks/SUV's) are 235/75 R15's. Does anyone know of any higher profile tyres suitable for our cars?

2. Have anyone had problems with the wider 235/75 tyres fouling the suspension?

3. I read somewhere (of course I can't find it now!), that when changing from crossplies to radials, that the castor or camber settings need to be changed. Can anyone shed any light on this?

4. Lastly, what sort of air pressures do people find best with the radials?

Thanks in advance!!

Jeff Jones
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Philip Sproston
New User
Username: phil2025

Post Number: 5
Registered: 7-2006
Posted on Sunday, 06 April, 2008 - 05:07 pm:   Edit PostDelete PostView Post/Check IP

To all - when fitting radials to cloud/s series make sure there a gap of approx 1/8" between the hub cap and the tyre. Had a customer fit a pair of Hankook 235/75/15 to the front in Darwin, got back to Sydney and found a groove cut into the side of the tyre nearly half way through the side wall. It could have been FATAL. Fitted Mastercraft 235/75/15, checked the hub cap had 1/8 all round, still trying to figure out the difference in the brands of tyres. Checked with long standing RR mechanic who said this hub cap is a known problem. It's a pity information like this does not seem to get out more.

Tyre Pressure - first read the maximum pressure on the side wall of the tyre, it should read 35psi max with full load, this is mostly on passenger tyres. If this is the case I have found 30 psi front and 32-34 rear to give a nice ride. If the max reads 65psi on the tyre wall, up the pressure by 2psi and note what the ride feels like, and adjust to suit. A new set of tyres is cheaper to replace than body mounts because of over inflation.
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John Mantello
New User
Username: john

Post Number: 9
Registered: 8-2004
Posted on Monday, 14 April, 2008 - 08:38 pm:   Edit PostDelete PostView Post/Check IP

Hi All, I have just fitted a set of Hankook 225/75/15 to my Cloud 1 and the ride is fantastic. The vehicle has traveled about 250 miles since the change over. No grooves to be seen yet!
I was recommended to go for the 235's but I kept to the same size as was on previously.
Philip is correct in the tyre pressure, I have 32psi all round and as I said the ride is great. This size tyre looks perfect to me in proportion to the vehicle.
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Jeff Jones
Experienced User
Username: jeffoir

Post Number: 26
Registered: 5-2007
Posted on Monday, 30 June, 2008 - 12:55 am:   Edit PostDelete PostView Post/Check IP

Hi again All,

Just an update- I have fitted 235/75R15 Bridgestone S375's to my two Clouds and have been enjoying the transformation others have described. They look great- they have a narrow white wall, and although there has been a small decrease in the height of the car I don't think this is noticeable. The wandering on poor surfaces has gone and handling improved. There's a little more noise on course chip road surfaces, but on the whole I'd recommend the radials over crossply's any day.

The hubcaps don't touch the tyres with the Bridgestones- thanks for the warning Phillip. I'm running the pressures at 32 psi all round, and the ride is good. I haven't noticed any rub with the wider tyres, so all in all a happy outcome!

Thanks for all the advice.
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N. Craig Bryant
Unregistered guest
Posted From: 68.6.89.150
Posted on Wednesday, 16 September, 2009 - 11:17 am:   Edit PostDelete PostView Post/Check IP

My friends,

First off, if I may address Mr. Payne's 1960 Silver Cloud II. If, when he bought the car, it was shod with "885-900x15" tyres, they were not the original tyres. 820x15 was the only size specified for, and fitted by R-R to the SC II.

Further, I cannot but be a bit 'non plussed' that this discussion continues ad infinitum. Rolls-Royce Motors never specified ANY radial tyre for any of the three Silver Cloud series. And I, for one, am not prepared to pit myself against the engineers at Rolls-Royce.

I have the factory service bulletin (I'm sorry I do not have the TSD number of this publication at hand) with regard to recommeded tyres on all post war models up to the early series SZ models. And R-R engineers, even after being long familliar with radial tyre applications, never recommended them for the Cloud or Phantom series. Indeed, the recommendation, even up to the end of production in 1993, of the Phantom VI, which shared the basic components of the Cloud series suspension and steering, still called for 890x15 bias ply tyres on those cars.

Indeed Rolls-Royce only specified radial tyres on the Silver Shadow after the introduction of "Compliant Suspension" to the model in 1970.

On a purely aesthetic note. It is fascinating to me that so many enthusiasts can 'wax eloquent' about Mr. Blatchley's styling of the standard saloon Silver Cloud, as having been so peerless that he "almost single handedly put the coachbuilders out of business", then blithely turn around, and with the stroke of their pen (to their cheque book), alter the proportions of the car he designed! I have never measured the standing height of a Silver Cloud that was not lower, with radials, than with the correct size bias ply tyre. Consequently altering Mr. Blatchley's design by changing the height to length ratio of the car.

Modern steel belted radial tyres also place undue stress on various steering and suspension components of the earlier cars. I believe this is not the fault of some design feature of the radial tyre per se, but because due to a greater tractability, owners of earlier cars shod with them, tend to take corners at higher rates of speed than they ordinarily would, damaging King pins and tie-rods etc. on cars that were never designed for those performance parameters.

Begging all of your indulgences for such a lengthy posting (although I could have gone on!).

(Message approved by david_gore)
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 418
Registered: 6-2006
Posted on Thursday, 17 September, 2009 - 07:34 pm:   Edit PostDelete PostView Post/Check IP

A few thoughts.

Although I agree that the Clouds look better on the radial height tyres and the wall markings are more aesthetically pleasing, and I prefer the less harsh ride, That's about as far as the argument should go really.

Firstly, how many Clouds are still standing at the height they left the factory? I bet the majority of cars have not had their springs re-set or shimmed.

With the Clouds and Shadows, their engineering is tried and tested, over engineered and very robust . . . but they are hardly cutting edge or go out on a limb just for the sake of progress or fashion.

They may not have specified Radial tyres but neither did they specify Electronic Ignition, Fuel Injection or Turbo chargers either.

Because the technology was not reliable and necessary?

Radial tyres were still not reliable enough. Even the Silver Shadow, Radials were a disaster, – Michelins as hard as wood and just as noisy, and Dunlops completely unable to stay round.

Why would R-R specify something that wouldn't work?

Now they work, why shouldn't people use them?

Strain on components - well that's the drivers choice. Most R-R drivers are sensible enough to drive their cars with care, respect and appreciation.

If somebody wants to drive their car to it's limits, they should - and will - pay for it in increased maintenance costs. But this is true if it's shod with Cross-Plys or Radials.
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N. Craig Bryant
Unregistered guest
Posted From: 68.6.89.150
Posted on Friday, 18 September, 2009 - 02:03 am:   Edit PostDelete PostView Post/Check IP

In response to Paul Yorke's comments:

"They may not have specified Radial tyres but neither did they specify Electronic Ignition, Fuel Injection or Turbo chargers either."

I couldn't agree more, and I have not, nor would I ever, modify a Silver Cloud/S series to any of those more modern pieces of engineering either.

(Message approved by david_gore)
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 422
Registered: 6-2006
Posted on Saturday, 19 September, 2009 - 07:33 pm:   Edit PostDelete PostView Post/Check IP

Craig,

LOL.

Out of context, but true in essence.

(Message edited by paul_yorke on 19 September 2009)
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Colin Silver
Frequent User
Username: colsilver

Post Number: 91
Registered: 8-2008
Posted on Saturday, 19 September, 2009 - 08:29 pm:   Edit PostDelete PostView Post/Check IP

Sorry Craig, I differ to your opinion.

My Cloud 1 came without seat belts, but they are now installed for safety.

I also run radials - the main reason being able to stop quicker than I would in cross ply tyres.

If people can't do these things just to remain concours - they should keep the 2 tonners off the road, unless they join a Morris 850 car run.
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N. Craig Bryant
Unregistered guest
Posted From: 68.6.89.150
Posted on Monday, 21 September, 2009 - 07:47 am:   Edit PostDelete PostView Post/Check IP

I have no desire to whip this horse anymore than anyone else. I make this addition to the conversation, only because Colin mentions adding, again, equipment not original to the car, in this case, seat belts.

In the U.S. we are not required by law to install any equipment, to any year model of car, that was not legally required at the time of it's manufacture. A miracle considering the "nanny state" in which we live these days.

I purchased my first Silver Cloud at age 17. In fact I took my test to recieve my drivers license in that car. I am now 56. In the last 39 years I have driven Silver Clouds hundreds of thousands of miles. I wish I had actually kept track of the miles! In that time, I have never had a collision in a single one of them. Indeed, I have never placed a claim with my insurer on one of my cars. That is not to say that I have never damaged one of my cars, but never to the extent that it exceeded my deductible!

So, consequently, I have never had any philosophical bent, based on my life experience, that caused me to modify to either radial tyres because of any theory of increased stopping ability. Nor have I ever installed seat belts in any of my Clouds, based on a theory of being thrown through the windscreen.

I suppose everyone's fears are quite real to them, and I encourage all to do what you feel you must.

(Message approved by david_gore)
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Jeffrey McCarthy
Prolific User
Username: jefmac2003

Post Number: 160
Registered: 5-2007
Posted on Tuesday, 22 September, 2009 - 12:11 pm:   Edit PostDelete PostView Post/Check IP

Interesting observations on seatbelt laws. I remember being told by some US friends years ago that they have a quiet chuckle every time they see an Australian cop show on TV. Even the bad guys belt-up before tearing off in the getaway car.

It's become so normalised here that I'd feel almost naked without one.
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Colin Silver
Frequent User
Username: colsilver

Post Number: 97
Registered: 8-2008
Posted on Wednesday, 30 September, 2009 - 05:23 pm:   Edit PostDelete PostView Post/Check IP

In the interests of safety, I want to whip the horse.

If a mature adult chooses not to wear a seat belt, they have that right - as long as they are in the front of the vehicle so they'll exit through the windscreen and not into a front passenger's head.

To drive a minor around unrestrained isn't humane.
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Brian Crump
Frequent User
Username: brian_crump

Post Number: 54
Registered: 2-2007
Posted on Wednesday, 30 September, 2009 - 06:08 pm:   Edit PostDelete PostView Post/Check IP

I agree 100% Colin - just so long as it does not frighten the horses should an accident occur and provided said person pays all his/her own medical-funeral-legal costs as a result and does not expect the taxpayer to contribute. Under those conditions I would be happy for anyone, except those near and dear to me, to drive without a seatbelt.
Regtards,
Brian Crump
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 443
Registered: 6-2006
Posted on Wednesday, 30 September, 2009 - 06:12 pm:   Edit PostDelete PostView Post/Check IP

Well, now the horse has been dug up again . . ..

Colin - what happens if you fly through the windscreen and injure a minor passing by ;)

Also , just a a clarification point. Is it inhumane to have a minor injure themselves - or is your concern about them injuring the front passengers? ;)

And what about adults in the rear?

Maybe based on experience, it's not worth having insurance either - if you've never had to use it?

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