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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Visit to the Dunlop Rubber Co. to discuss the development of 'Fort' and 'Super' model tyres.

Identifier  ExFiles\Box 58\1\  Scan067
Date  1st September 1928
  
To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}
c. to BJ. Wor.{Arthur Wormald - General Works Manager}
c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer}
c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer}
c. to SG.{Arthur F. Sidgreaves - MD}

X5820

Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}3/LG25. 9.28.

DUNLOP RUBBER CO. X4050 X7820
X5820 (crossed out) X8005 x2446

We visited the Dunlop Rubber Co. on the 24th.
inst. We discussed with them the question of tyres. Their
opinion at present is that the 6.75" tyre for the 40/50 and 6"
tyre for the 20 HP. which we are using as standard are too
susceptible to variations in tyre pressure. To overcome this
they have strengthened up the casing of both tyres, the modified
samples of which they term 'Fort' models. Unfortunately, in
doing so, they have increased the effective rolling radius of the
tyres by about .250 / .375" and the weight by 6 lbs. or so per
tyre, the cost of the tyre having gone up proportionately.
We propose to try these tyres, but except for
Colonial and Continental conditions it seems questionable
whether they are really necessary.
In addition to the 'Fort' series, the Dunlop Co.
are introducing a still heavier tyre termed the 'Super' model.
This might prove of interest in India where Rolls-Royce cars are
used for hunting and so far balloon tyres have proved too vulner-
able for cross-country work.
In connection with the 'Super' tyre, it is
interesting to note that on a 20" rim its rolling dia. is only
very slightly less than our present std. 6.75" tyre on 21" rims.
One point which we wish to determine is
whether the 'Fort' and 'Super' tyres on the 21" rims will
contd :-
  
  


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