RetroFord Magazine Longstone Tyres Article

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RetroFord Article Classic Cars

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Q&A

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TYRE TECHNOLOGY

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Discover the importance of tyres for an older Ford, whether wider tyres are better and which original brands are still available. Dougal Cawley at Longstone Tyres has the answers.

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Q: What’s the difference between a cross ply tyre and a later radial tyre?

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A: The clever thing about a radial is that as the sidewalls flex the tread stays flat on the road. This is particularly helpful in the corners where a cross-ply would flex its tread while in contact with the road, dramatically decreasing grip and longevity. The radial has a belt inside the tread that is independent of the sidewall carcass to hold the tread flat.

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Q: Is it simply a moneymaking scam to recommend changing tyres in sets across an axle and keeping with the same brand?

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A: Under emergency braking, one tyre will lock up before the other which could well lead to a spin and loss of control. So, tyres should be changed in pairs. It is not the law, but we buy good tyres not so much for everyday driving but so that if that emergency does occur, we can maintain control of the car.

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Q: How long do tyres last, even if the tread depth is sufficient?

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A: For an MOT, if the perishing in a tyre reaches a point when the fibres inside the carcass are visible then it is a fail. This is rational because if you can see them, grit can get to them. Also, when a tyre is ten years old you should just change it. There are the visible issues such as perishing, but we are also concerned about the internal structure, and without doubt a tyre’s performance when ten years old will be bad.

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Q: Does a wider tyre always provide better handling?

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A: No, but wider tyres often provide more grip in a straight line if the load is there to benefit from it. Wider tyres do not give better handling, thinner tyres give better, more progressive handling. Wider tyres spoil the handling and tend to make a car break away more violently and snatch. A wider tyre will only give more grip in the corners if you have the stiffer springs and greater adverse camber of a more modern car chassis which all work together to keep that footprint on the road. On an older chassis, as the car leans, so does the wheel and it gets to the point where it suddenly lifts a large portion of the tyre off the road creating a sudden loss of grip. Not what you want when swerving round a child that has suddenly appeared from behind an ice cream van.

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Q: Why is it dangerous to drive a car with a tyre that’s almost flat?

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A: The tyre will overheat, resulting in a greater risk of damage and a blow-out. Lower pressure in tyres also reduces its directional stability and creates slushy handling in the corners.

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Q: Are there any limits as to how wide or how narrow you can go with a tyre on, for example, a 6in-wide wheel? For example, you said in the December 2024 issue of Retro Ford that the Capri 280 Brooklands used a 195/50R15 P7 tyre (which is no longer in production), but the slightly larger 205/50VR15 P7 can be fitted that’s 10mm wider than the original.

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A: I think the Brooklands is an interesting example where a car manufacturer has decided they went a bit far with the 205/50R15 P7 and stepped back to a 195/50R15 P7 for a bit more progressiveness over ultimate straight line grip, because cars are principally nicer to drive on thinner tyres. There isn’t currently a 195/50R15 as well-suited as the P7, which is why for now we recommend the 205/50R15 P7. A rim can fit a wide variety of tyres. A 6in rim can fit a 235/80 profile tyre right down to a 165/50 section tyre. The lower the profile of a tyre, the slimmer the option of rim sizes it can fit. It is also worth noting the rim widths we recommend on all our individual tyre pages are the ETRTO [European Tyre and Rim Technical Organisation] recommendations as to when a tyre will perform at its best, but there is scope for stretching a tyre on to a rim. The overhang of a tyre is predominantly there to protect your wheel from the kerb.

Recommended rim widths for older Fords on 13in wheels are:

• 145R13 PIRELLI CINTURATO CA67 3.5in – 5.0in
• 155R13 PIRELLI CINTURATO CA67 4.0in – 5.5in
• 165R13 PIRELLI CINTURATO CN36 4.0in – 5.5in
• 175/70 VR 13 PIRELLI CINTURATO CN36 4.5in – 6.5in
• 185/70 VR 13 PIRELLI CINTURATO CN36 5.0in – 6.5in

Cars like the Escort, especially the majority of rear-wheel-drive Escorts, would have left the factory with a 4.5in rim and a 155R13 tyre. You can actually fit 175/70R13 Pirelli Cinturato CN36 on to that 4.5in rim. The 175/70VR13 Cinturato CN36 was fitted to the RS2000 on to 5.5in or 6in rims because the wider wheel presents the wider tyre to the road with more stability, gaining more ultimate grip because of course these sporting cars have different geometry and suspension to keep that wider footprint in contact with the road. Simply fitting a wider tyre to your car does not always give you more grip, unless the other details are in place.

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Q: Is a lower profile tyre really any better?

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A: It can present more tread to the road if you have the chassis geometry to suit it. And there is less risk of sidewall deflection, but there is also a greater risk of producing skittish handling and a low-profile tyre does give a rougher ride than a tall sidewall.

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Q: If a Ford, such as a 100E, was originally equipped with a cross-ply tyre (such as a 520-13), should a more modern radial tyre be fitted instead?

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A: The choice is yours; however, a proper period radial tyre, will make a 100E better suited to today’s modern roads. There are so many dual carriageways where we can maintain cruising speeds of over 50mph, so you don’t really want to be wandering around the road on a cross-ply. Pirelli makes a 145R13 Cinturato CA67, which is absolutely perfect for these cars. It would have been the best upgrade in the day for these cars and I would suggest, as an improvement for the driver, it is even more poignant today. Because that 145R13 tyre fits such a massive range of cars like MG (Midget) and Healey Spridgets, Triumph Spitfire, Lotus Elan, Allegro, Marina, Ford Anglia, Prefect, Pop, Cortina etc, the price is extremely good for such a high-quality classic car tyre.

All that said, I drive 1920s Model A Fords on a regular basis over thousands of miles, and I do that all on cross-ply tyres. You don’t want radial tyres on pre-war cars.

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Q: Should inner tubes be used on any Ford wheels and are they a good idea?

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A: Ford were early advocates of the tubeless wheel. Looking at my period fitment guides, right back to the 105E of the late 1950s, it looks like Ford were running tubeless wheel and tyre systems. However, early tubeless systems were not really as good as they are today. A tubeless wheel rim of today’s design will have a hump inboard of where the tyre sits on the rim. This is to stop the bead slipping into the wheel well under cornering forces. At Longstone Tyres we suggest that if it doesn’t have that safety hump, fit an inner tube. If you are dubious about whether your wheel is designed to run tubeless, or an alloy wheel that has become porous, simply fit an inner tube. We sell the Michelin inner tubes because the quality is exceptional. Do not fit inner tubes in tyres lower than a 70 profile.

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Q: If the steering on your Ford feels too heavy, can changing the tyres make a difference (assuming there are no issues with the steering that cause it to feel heavy)?

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A: Yes. Simplistically, less of a footprint makes the steering lighter. Your standard Capri on a 4.5in rim 165R13 Cinturato CN36 would have dramatically lighter steering than the X-Pack on its 205/50R15 P7. The original Fiesta on 135R12 would have dramatically lighter steering than the XR2 fitted with 185/60R13 tyres.

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Q: The Pirelli Cinturato P7 was seen as the ultimate tyre, having been fitted to Fords such as the Capri X-Pack (205/50VR15), 280 Brooklands (195/50R15), along with the P700-Z that was used on the 1992 1996 Escort RS Cosworth. Do you still regard these as the ultimate tyres?

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A: These are still the ultimate tyres for these cars. No manufacturer since then has wasted their efforts making tyres that will handle better on this style of chassis design. Their focus moves on, as does the chassis design and steering of modern cars. However, manufacturing build quality has improved, and today’s batches of Pirelli Collezione [collection] tyres benefit from modern manufacturing facilities. Over the years, the chemicals and materials we are allowed to make tyres from has moved on to greener pastures. As a result, while these period tyre carcasses are presenting the footprint to the road in a manner that suits your car, that footprint is made up of modern compounds that move water far better than they did in the day. In recent years, the German classic car magazine Auto bild Klassik has done back-to-back tyre tests against other classic tyres and modern contenders in which the Pirelli repeatedly comes out smelling of roses and, in most parts, blows its contenders into the weeds.

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Q: Have you ever been caught out by listing a specific tyre, only to find it was never originally fitted?

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A: Yes and no. Pirelli’s 10-page fitment guide lists a 205/55R14 Cinturato P7 as a Capri tyre. I posted something about this on a load of Facebook groups and there was a bit of a stir of people telling me it was rubbish, and it was never fitted. Then someone from Italy chipped in and said that the 205/55R14 Cinturato P7 was factory fitment for some Italian models of Capri. Who knew? Anyway, 205/55R14 is a bit of a silly size because the only other fitment we can find for it is the couple of years of Maserati Biturbo that it fits, the majority of which have of course dissolved some years ago. However, Pirelli made the tyre anyway, which is good news for the vast array of Italian Capri fans, or local Capri fans with 14in wheels.

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Q: What about the Dunlop SP Sport? Is that still a popular tyre on older Fords?

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A: There is no doubt that the Dunlop SP Sport is a very cool-looking tyre. Recent productions of the SP Sport were no longer actually made by Dunlop themselves. Dunlop has just been swallowed up into a massive tyre conglomerate. Sadly, the Avon factory that has been making the SP Sport was closed in 2024. A new manufacturing plant is being sourced and we hope to have them available again soon.