Jaguar World Magazine Longstone Tyres Article

Longstone Tyres' Dougal Cawley Featured in Jaguar World Magazine

We are excited to share that Longstone Tyres was recently featured in the October 2024 issue of Jaguar World Magazine! In this interview, our very own Dougal Cawley offers expert insights into the importance of choosing the right tyres for classic Jaguar cars. From discussing the impact of wider tyres on handling to comparing the benefits of cross-ply and radial tyres, this Q&A session dives deep into tyre selection and maintenance for classic Jaguars and beyond.

The article covers a wide range of classic Jaguar models, including the Jaguar Mk2, E-Type Series 2, XJ6 Series 1, V12 E-Type Series 3, and the XJ12, XJS, and XJ40, providing a unique insight to the rubber used with each of these iconic vehicles. While the article focuses on Jaguar models, the advice Dougal provides is relevant to all classic car owners. The principles of tyre selection, performance, and safety apply universally, making this an essential and interesting read for anyone looking to get the most out of their classic car. Whether you’re considering a tyre upgrade or just want to ensure your classic car is performing at its best, this feature offers invaluable advice from one of the leading voices in the field.

See the full transcript for the article below

To find tyres for the cars mentioned in this article, see the links below.

October 2024 | Jaguar World Q & A

Jaguar World’s technical advice service - Edited by Rob Hawkins

In Touch with the Tarmac

Can the rubber that connects your Jaguar to the road really make a difference? We ask classic tyre specialist Dougal Cawley of Longstone Tyres

Q: Does a wider tyre always provide better handling?

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 around a child that has suddenly appeared from behind an ice cream van.

Q: Is a lower profile tyre really any better?

A: It can provide more tread when in contact with the road if you have the chassis geometry to suit it. 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.

Q: If a Jaguar was originally equipped with a cross-ply tyre, should a more modern radial tyre be fitted instead?

A: Sometimes. For example, the Jaguar Mk2 was originally equipped with Dunlop RS5 cross-ply tyres on 15-inch diameter wheels, but Dunlop is no longer manufacturing classic road tyres. I recommend upgrading to the period radial tyres instead, including the Pirelli 185VR15 Cinturato CA67, which costs around £1,000 for a set of four. Michelin makes a rather special 180HR15 XAS tyre that’s a little cheaper and, in my opinion, better for non-power-assisted models because these tall, thin tyres keep the steering light and precise.

Pirellis are perfect because they are genuine period sports car radial tyres with a period carcass made to handle well when fitted to a chassis from that period or used as an alternative to a cross-ply. The attraction to the 180HR15 Michelin XAS is that it is a slightly odd special tyre size that is tall and thin, thereby keeping the steering light. Also, the XAS was developed in conjunction with the Citroën DS to make it stop wandering at cruising speeds on the increasing number of dual carriageways that were popping up over Europe in the 1960s. In other words, it was making cars like a Citroën DS or Jaguar Mk2 more suited to modern roads.

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

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.

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

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.

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

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 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.

Q: Why is driving with a tyre that’s almost flat dangerous?

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

Q: Some Jaguars had tyres specifically designed for them, such as the Dunlop ER/70 R15 for the XJ Series 1. Is this still available and still worth fitting?

A: The Dunlop ER/70 R15 was a groundbreaking tyre. The first production car to fit the new low-profile tyre technology was the Jaguar XJ6 Series 1, and this car left the factory fitted with Dunlop’s new ER/70 R15 SP Sport. The ER/70 R15 SP Sport also acquired the nickname Aquajet. The ER/70 R15 Dunlop Aquajet tyre was also fitted to the V12 E-type Series 3.

In the mid-1970s, Jaguar contacted Pirelli with the need to have a better quality, more consistent tyre. Jaguar and Pirelli then worked together to develop the Cinturato P5. A few years ago, Jaguar contacted Pirelli again, as their interest in their heritage grew, they wanted to again have the best possible tyres for their luxury XJ6, XJ12, XJS, and XJ40 cars. They asked Pirelli to produce the P5 again. The current range of P5 benefits from what they learned in the period about the best carcass for these cars but now benefits from modern quality control and modern compounds specifically improving their wet grip. These modern P5 tyres were tested by Jaguar and given the J homologation.

Q: The E-type Series 2 was fitted with tubed radial tyres from Dunlop. Is it better to upgrade to tubeless instead?

A: Part of the move to the Series 2 was fitting tube-type radial tyres as standard, and Jaguar fitted Dunlop 185VR15 SP Sport Aquajet because they were made next door in Birmingham. The Pirelli Cinturato was really the sports car tyre of choice in the period, if money was no object, and if it is progressive, sporting handling you are looking for, Pirelli Cinturato is still the tyre. The tyres available for these cars today are tubeless-type tyres, which means they can be run tubeless but only if fitted to a wheel that is suited to being used without an inner tube. E-type Series 2 wheels need inner tubes. All wire wheels should have inner tubes. We have seen too many failures with tubeless wire wheels to trust them.

Q: Are inner tubes a good idea?

A: Good-quality inner tubes are worth fitting if you are in any doubt about whether your wheels are tubeless. All wire wheels should be fitted with inner tubes. However, you should not fit an inner tube in a tyre lower than a 70% profile.

Q: If a Jaguar has a power steering conversion, should the tyres ideally be changed to suit?

A: No. A car’s chassis that is developed in line with a cross-ply or full-profile radial (such as a 185R15) tyre will handle best on a quality period tyre of that size. A power steering kit will help overcome the heavier steering caused by oversize tyres. If you are going to fit oversize tyres, a period tyre will diminish the derogatory effects on the progressive handling. A more modern 65% or lower profile will have dramatic effects on handling, which can be dealt with by the stream of clever upgrades developed by the likes of Eagle E-Type, which are fantastic. However, ask yourself how far you want to stray from a classic Jaguar.

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

A: Yes. Simplistically, less of a footprint makes the steering lighter. Take the classic S-type, which was initially fitted with Dunlop RS5 (640 H15) cross-ply tyres that were replaced in June 1964 with SP41 radials. If you consider your steering to be heavy with either of these tyres, the 180HR15 Michelin XAS is superb and offers lighter steering and also the 185VR15 Pirelli Cinturato CA67 radial tyre. There is a 185x15 Dunlop SP Sport Aquajet that Dunlop used to make. However, we would still recommend the Pirelli or Michelin.

The Michelin 180HR15 XAS is the same height as a 185R15 but is actually closer to the original 640-15 because it has a nice thin rounded footprint, which keeps the footprint a bit lighter and doesn’t load up the steering as much as a more modern 185. The asymmetric carcass and tread pattern makes a Sixties classic drive in a straight line better than anything else. Modern squarer-shouldered tyres will give tracking [tramlining] on motorways and heavier, vaguer steering.