Tubeless tyres

[nigel jarrett]

After reading the articles in the Jowetteer about tubes in tubeless tyres and after having a nightmare fitting tubes with 175 tyres .I was wondering if it's poss to run them without tubes successfully .

[David Morris]

Hi Nigel,

My recommendation is just don't fit tubeless! The cars were never designed to run on tubeless, which, if larger in cross section than cross ply, will result in heavier steering, especially at slow speeds. Possibly they will result in more wear too on the suspension and front bearings, which are fragile little things that should have been altered for rollers years before the factory finally recommended a very late design change. Also, the sizes available in tubeless may give clearance problems on the rear tyres inside the wheel arches.

People have also found tubeless tyres don't fit the spare wheel tray very well.

I have run my Javelins on cross plies with, thankfully, no problems with tubes. Just go original and smile! You will get a wonderfully pliant steering and comfort. Yes, they will seek out things like poorly filled trenches in the roads and keep you on your toes! But they work well!

I know several owners who, after battling with tubeless for years, have reverted to cross plies and sit back with a smile and a sigh of satisfaction!

All the best,

David

[Keith Clements]

I would never run tubeless tyres on rims that were not designed for the purpose. I have always run with tubes and have been running on crossplys on the Javelin until two years ago and radials on the Jupiter since the early 1970's . I have driven many Javelins and Jupiters on crossplies and radials in some demanding conditions and certainly prefer radials as they corner and brake a lot better. BUT there are good crossplies and bad radials. You can usually tell the difference by the price. I have just paid well over a £1000 for a set of radials for my Jupiter having put the same tyre on the Javelin two years ago. Of course bought via JCS. These are to replace a set of radials with tubes fitted in 1998. Yes I did have one puncture in Spain (possibly caused by going at over 95mph for 60 miles to make a time control) or being pounded in the Dordogne by some large potholes. Those same tyres also took us around Europe and were pounded by the Latvian roads with a puncture surfacing when we were in Belgium. I also had a puncture on the way to Scandinavia in Newcastle just before we went on the ferry. So not many in 18 years of punishment on forest stages, Sahara piste and all manner of potholed roads.

Regarding issues with tubes. Yes we have had some trouble with tubes and the general consensus is that the wrong size tube was fitted. A tube an inch smaller than the rim size seems to be the answer. Always fit bands to the rim to cover the welds and you usually need an adaptor to fill in the larger than normal valve hole. You will get issues if you fit larger width tyres than 175 and some have experienced issues on the Javelin with rubbing on the body work even at that size. Yes you may have to expand the spare wheel carrier a bit on the Javelin or extend the carrier on the Jup. But IMHO it is worth it for the greater safety in today's traffic. Note the issues we had on the LA to Arctic circle trip with punctures was with crossply tyres.

If you only drive 20 miles here or there to a show then stay with the original size and type of tyre.

One issue is keeping tyres out of the sun for extended periods as this can rapidly deteriorate the rubber. Even a couple of years can make them unserviceable.

Another issue is finding a tyre fitter who actually knows what they are doing. Try to find one who does commercial vehicles.

[Srenner]

Tubeless tires require a "safety" rim profile. The safety feature helps keep the tire bead held to the rim under adverse conditions by having a pair of safety humps extending inward. Jowett wheels lack this style rim.

I agree with Keith on the value of quality radials, though I have also run crossplies for forever. After the Arctic trip the car got a set of Michelin X radials (Longstone Tyres). Should have done that before the trip!!!!!! Massive improvement.

Tubes are starting to become an issue. The literature on tubes makes a distinction between cross-ply and radial tubes, but no one I ask seems to know why. Almost all the tubes available in the USA are Chinese and are visibly inferior to the old ones (usually made in Korea). Michelin makes tubes in Serbia, but weren't readily available on my re-tire schedule.

Yes, use a 15" tube. Ted Miller told me that back in '89 when I started my first restoration. A modern 16" tube will fold over itself on the ID, creating a crease that will eventually leak or burst.

[David Morris]

Hi All,

Some useful comments already! There was a remark in the current Jowetteer about the difficulty in getting our size of wheels balanced. It's not the tyre diameter but the large hole in the wheel centre that causes the difficulty. I found that you need to seek out an old established tyre company that has the large mandrels needed. The company I went to had the mandrels but they were covered in dust tucked away under a bench and clearly hadn't been used for a long time.

So, research who to use and probably the older the company the better? Perhaps companies servicing commercial vehicles might be more used to the large centre holes?

All the best,

David

[nigel jarrett]

Thank you for all your comments,gives me something to think over ,I had fitted 175 taxi tyres with land rover inner tubes two years ago by a local main line tyre firm and have only covered about 1000 miles I found the ride improved and Road noise decreased and yes the steering is heavier and being an earlier PA with the narrower rear axle I had no problem with clearance on the rear wings .but have always been slightly concerned

[Keith Clements]

The heavier steering MIGHT be caused by a subtle change in steering geometry due to the position of the contact patch. This is where the king pin inclination, castor and camber angles combine to hit the road surface. A higher rolling radius tyre will tend to move the intersection outwards and a wider tyre put more force against the turning motion. The latter is governed by the castor angle. To a minor extent the castor can be regulated by the position of the king pin in the upper link. Slight adjustment is possible on metal suspension with the screw thread and washers can be used on rubber suspension. All this assumes that you have laboriously checked your steering geometry in the first place.

Tyre pressures greatly affect the steering feel. High pressure makes it lighter. Radials require more pressure than crossplies because the wall needs more support. The aim is to get as much contact patch as possible but also to provide wall support when cornering hard.

175 tyres on standard rims tend to bulge over the rim and the wall does not sit vertically. Widening the rims by inserting a band or using a wheel from another car with a Jowett centre or having new wheels made makes a huge difference to the contact patch size. The tread will now sit flat on the road rather than being curled up. However, if you do fit wider wheels, the steering geometry needs to remain the same so adjusting the offset of the wheel then becomes necessary.

The tyres I would recommend are 165HR16 Avon Turbosteel from JCS.