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To be correct & fill in the blanks the stock is a 185/(79/80)/15 for a Mk2. The 69 Daimler V8 was still Mk2 based waiting for the Daimler version of the XJ6 to be produced & there was the Sovereign where the same applies. Daimler dealers had to wait but needed something to sell other than the Majestic Major which was expensive & past it's sell by date. The Daimler V8 & the Sovereign were the last to be manufactured & sold of the compacts until the XJ6 based Daimler was produced. Read this thread!
Last edited by Glyn M Ruck; May 20, 2023 at 06:20 PM.
To be correct & fill in the blanks the stock is a 185/(79/80)/15 for a Mk2. The 69 Daimler V8 was still Mk2 based waiting for the Daimler version of the XJ6 to be produced & there was the Sovereign where the same applies. Daimler dealers had to wait but needed something to sell other than the Majestic Major which was expensive & past it's sell by date. The Daimler V8 & the Sovereign were the last to be manufactured & sold of the compacts until the XJ6 based Daimler was produced. Read this thread!
The advantage of going to a 16" or 17" keeping the height close to stock will be the availability of high quality performance tire as those will not be available in 15" or too tall of a tire in most every case. Besides the width of the tire the next best thing for handling is the quality of the tire and with most of Jag owner here whom do not drive the miles I do yearly, it is best to get a soft performance tire to give you great handling....
Agreed! ~ if you want to go up from the standard 15" to a 16". Prior to aspect ratio being shown on the sidewall all tyres were 79/80 profile. It was the global standard. The lower aspect ratio tyres started with the 70 profile.
Last edited by Glyn M Ruck; May 21, 2023 at 03:30 AM.
Not withstanding scrub, steering geometry and speedometer error does anybody know how a Mk 2 handles with these low profiles?
Getting back to the original question of how a Mk2 handles with a lower profile tyre, possibly with a larger wheel, none of us know for sure. Primaz has genuine experience with the tyres, but his car is an S type with IRS and the suspension is modified to make the best use of the rubber. Primaz's car and the performance of different sizes on XJ series suggest wider rubber on a larger wheel should work well so long as you don't go too far. A 16 inch wheel with enough rubber to maintain the rolling radius might do very well. You could go as far as Primaz, but keeping a wide tyre vertical under hard cornering requires suspension stiffening that might all get very complicated on a car that's had its roof cut off.
Edit: I should have added Bill is OK with his tyres that are a little wider. And, back in the day, many used series 1 XJ 15 inch wheels and tyres. It required grinding a little off the bottom ball joint cap. It's not an option worth following now, but is indicative that a modest increase in tyre width works well.
Last edited by Peter3442; May 21, 2023 at 04:57 AM.
The performance of a tyre is weight over contact patch size. Too large a contact patch size & for the same weight and performance of the tyre will drop off. Wider is not always better from a handling perspective.
The Honda Prelude is a case in point. Honda optimised the standard Michelin tyre size for best handling performance. Go any larger/wider and the handling is immediately compromised. (all things being kept equal and that contact patch being kept in contact with the road in hard cornering taking into consideration weight shift ~ The Prelude has such a wide track that it corners virtually without roll). Anyone that has run a racing team knows this. I have run a racing team both bikes & cars.
The OP ~ having chopped the top off the car might have to worry about some stiffening long before tyres.
Last edited by Glyn M Ruck; May 21, 2023 at 08:03 AM.
Edit: I should have added Bill is OK with his tyres that are a little wider. And, back in the day, many used series 1 XJ 15 inch wheels and tyres. It required grinding a little off the bottom ball joint cap. It's not an option worth following now, but is indicative that a modest increase in tyre width works well.
Spot on. Bill has moved from a 185 to one profile lower 195's
Peter this is the photo of 185 X 15's that you are likely referring to. It should however be noted that none of these are mounted or inflated to equal pressure. All fitted to classic Jags OE at some time ~ The monster 2nd Right was under the old British cross-ply rating e.g. 640 X 15. It's a Dunlop RS 5. Tyre 2nd to Left is a Dunlop SP41 or SP73 dependent on market. It was known as an SP73 in SA as an example. Cross ply tyres ran at lower pressures than Radials where max 40 psi was dictated by Jaguar & the tyre manufacturers. ~ Source of picture, the UK E Type forum.
I'm sure you recognise them left to right. Michelin, Dunlop, Good Year, Pirelli, Avon, Dunlop, Michelin.
Sorry to admit an error on my behalf 3rd from left is also a Michelin. Tread pattern similar to that preceding the Good Year Grand Prix. It even has Bibendum on it SMH. Silly mistake. Jaguar predominantly fitted Dunlop RS 5 (X-ply whitewall US market) & SP41 OE to sedans. E Type saw more Pirelli & Michelin.
Last edited by Glyn M Ruck; May 21, 2023 at 01:21 PM.
Still, the point remains that the radials look significantly different. It's hard to imagine that, even after inflation, they will have the same rolling radii and footprints.
From stock there should be no issues to go to a 215 wide tire or a 205 as that is not wide enough to cause any issues with clearance. If you go with a 17" you will have more choices on quality performance category tires and with the right height tire you can keep the same height as stock. I think a good upgrade would be a 16" and Sumitomo is one of the only performance options as they offer a number of sizes in 16" as well as 15" that would fit the stock body with stock suspension that are true performance tires https://www.tirerack.com/tires/tires...omCompare1=yes
You can get the Sumitomo in 205/65/16 which is the exact height of stock and a the only performance tire available
As tire manufacturers make advancements in quality of compounds, tread, etc. those are only offered in the performance category NOT the old school high profile tire stock sizes. If you go with stock sizes you will miss the better handling of the newer technology that has advanced over the decades. That is just the reality the good performance tires are only going to be available in sizes that newer cars use so that they can sell larger quantity of tires. Thus you need to go to larger diameters than stock to gain quality rubber technologies.
For a 15" to me it is hard to get an improved quality tire without dropping the height about 1.9% at 26" instead of the 26.5 of stock and there are only a few performance options, the Sumitomo HTRA in 205/65/15. In 15" there are really NO performance tires available that are close to stock height. The options are low technology tires or some mediocre non performance tires like the BF Goodritch Radial T/A or the Cooper Cobra Radial G/T both in the 205/70/15" In the stock height of using a 205/70/15 you would gain a little wider tire but there are no performance category tires in that size.
Still, the point remains that the radials look significantly different. It's hard to imagine that, even after inflation, they will have the same rolling radii and footprints.
You are absolutely correct Peter which is why there is a long listing of actual sizes at Tirerack fitted & inflated. As I've said ad nauseam ~ If you want to remain stock for shows etc. the highest performing tyres are 185 VR 15 Michelin XVS or 185 HR 15 Michelin XVS-P. They are very high performance tyres and would satisfy most. In fact people that run them are delighted with the standard of handling. You don't need the VR rated version because our cars wont do 130mph so the HR version at 120mph is suitable but if you want the VRs they are available. They have very good rubber compounding & are built to the latest carcass standards hence achieving a VR rating with ease. Remember in countries like Germany you have to support your claims on the tyre. ADAC test them for Government. They are true performance tyres. People who think otherwise might be very surprised. One can take a step back to the old XAS & even they are good. Michelin spends more money on research than any other tyre company in the world & by some margin. They are also the largest tyre company in the world by tonnes of rubber milled. On a standard Jag compact from our era I would never go higher than a 205 for best handling.
Last edited by Glyn M Ruck; May 22, 2023 at 08:18 AM.
Actually the Dunlop Sport Classic will edge out in performance over the Michelin but those are still old 70's technology and do serve a purpose to keep classics on the road for people whom want to keep everything stock, but they are NOT anywhere near the performance of modern tires. Putting a 205 or 215 with a true modern Performance category tire is far better for performance.
Not true ~ they are right up to date in every respect unless you profess to know more than the Technical Director of Michelin. I don't think you do and neither should others.
The Dunlop Brand is owned by Goodyear, Sumitomo & Continental and it's not their primary concentration in any way. They all concentrate on their own brands.
Michelin tests all of it's competitors tyres. They know what they are talking about.
I will listen to Eric-Philippe Vinesse long before you.
Last edited by Glyn M Ruck; May 22, 2023 at 10:21 AM.
...and, so long as original appearance is not a priority, a modern Michelin 205/60 16 V or H and similar will save £ 100 or so per tyre in the UK. They even save over classic sizes from the likes of Blockley and Vredestein.
It all depends on what you want from your car, how much you use it, how you drive it. Personally, I'd go for 16 inch wheels and a tyre section to maintain rolling radius, but I understand the views of those who go either side of my compromise.
...and, so long as original appearance is not a priority, a modern Michelin 205/60 16 V or H and similar will save £ 100 or so per tyre in the UK. They even save over classic sizes from the likes of Blockley and Vredestein.
It all depends on what you want from your car, how much you use it, how you drive it. Personally, I'd go for 16 inch wheels and a tyre section to maintain rolling radius, but I understand the views of those who go either side of my compromise.
Yes Peter ~ true ~ but I will listen to Eric-Philippe Vinesse long before anybody on this board. As I've said before I will be fitting 185 HR 15 Michelin XVS-P's to my car because they are all I need & there are insurance implications irrespective of how you drive your car. The S Type is accepted by the insurance industry as an absolute max 120mph car here. In fact it is classified in the 190 kph class. Thanks to the Automatic.
Last edited by Glyn M Ruck; May 22, 2023 at 11:02 AM.
I was comparing between his, that is Michelin's, tyres. Obviously, Michelin can sell types they make by the tens of thousand more cheaply than those they produce in the hundreds. My point was that it's up to us if we want to take advantage of that.
The old car world, in fact the whole world, is full of experts and non-experts who will tell you any story they can get away with. One of the worst in this context is "These cars were designed for such and such ancient tyres." Speaking as an over qualified engineer, who has worked in research and in design, we aren't actually that clever, and I'm sure Bill Heynes would agree with me. No one had ancient cross-plies with ancient rubber formulations in mind when they set out the 2.4 Mk1 suspension. Yes, they produced something that worked with them, but they certainly hoped for something better (we always do). They eventually got a better tyre with the XJ6. And anything the XJ6 can use, the Mk2 can certainly be adapted to use.
I think the XJ6 originally had 205/70WR15 Pirelli P5 tyres and in my research just recently to get new tyres for my S Type it appears Pirelli has just started remaking the P5.
From Longstonetyres.co.uk
Pirelli P5 Tyres
The PIRELLI P5 came out in the late 1970s.
The P5 was developed by PIRELLI in conjunction with Jaguar to fit the XJ6, XJC, XJ12 & XJ40.
Designed for comfort, performance, and a quiet ride.
PIRELLI now produce the 205/70WR15 P5 for the XJS & XJ6, the 215/70WR15 P5 for the XJ V12 & 225/65R15 P5 which was OE on the Jaguar XJ40.
[QUOTE=Glyn M Ruck;2644596]Not true ~ they are right up to date in every respect unless you profess to know more than the Technical Director of Michelin. I don't think you do and neither should others.
The Dunlop Brand is owned by Goodyear, Sumitomo & Continental and it's not their primary concentration in any way. They all concentrate on their own brands.
Michelin tests all of it's competitors tyres. They know what they are talking about.
I will listen to Eric-Philippe Vinesse long before you.
Both the Dunlop and Michelin were part of the few vintage tires that could be called performance but it was really more performance based on 1960's standards. If you compare them to a modern performance tire then they would be ranking low on performance, which is why going with a 16" or 17" gives you the options of modern performance tires. That is just reality, tire companies will always phase out tire sizes not used anymore. Then you are left with substandard tires that are over priced for what performance you get, but if you are a purist like yourself then there is no option than to spend big money for old technology.
You can get the Sumitomo 205/65/15 which is same height as stock for $111 each or buy your Michelin XVS for $352 each?
I think the XJ6 originally had 205/70WR15 Pirelli P5 tyres and in my research just recently to get new tyres for my S Type it appears Pirelli has just started remaking the P5.
From Longstonetyres.co.uk
Pirelli P5 Tyres
The PIRELLI P5 came out in the late 1970s.
The P5 was developed by PIRELLI in conjunction with Jaguar to fit the XJ6, XJC, XJ12 & XJ40.
Designed for comfort, performance, and a quiet ride.
PIRELLI now produce the 205/70WR15 P5 for the XJS & XJ6, the 215/70WR15 P5 for the XJ V12 & 225/65R15 P5 which was OE on the Jaguar XJ40.
Rob. The SA Built XJ6 was launched with the Dunlop SP73 ~ Good for Beach Buggies rear. It was basically the tyre known as the SP Sport Aquajet in the UK but with more suitable compound rubber for our hotter conditions & a few other mods. Yes they were a 205/70.
Last edited by Glyn M Ruck; May 22, 2023 at 12:43 PM.
[QUOTE=primaz;2644629][QUOTE=Glyn M Ruck;2644596]Not true ~ they are right up to date in every respect unless you profess to know more than the Technical Director of Michelin. I don't think you do and neither should others.
The Dunlop Brand is owned by Goodyear, Sumitomo & Continental and it's not their primary concentration in any way. They all concentrate on their own brands.
Michelin tests all of it's competitors tyres. They know what they are talking about.
I will listen to Eric-Philippe Vinesse long before you.
[size=13px]
Primaz Bla! Believe as you wish "[/size]The tires are missing a DOT symbol. According to NHTSA, that may cause inappropriate applications that increase the risk of a crash.
I will listen to Eric-Philippe Vinesse long before you. That's all cobblers by amateurs & not even the tyres we are discussing in the first case. I see no reference to a control tyre in any of that testing rendering it meaningless and in the 2nd case I'm far more interested in ADAC testing where they do things properly. The DOT symbol ~ who cares?? Those tyres will just be sold in other markets that don't care about DOT symbols like SA, Aus, EU, Asia etc. etc ad infinitum. Just about the only thing that the world bothers about related to DOT is brake fluid. A whole 1 item that has become a standard. What an expensive joke.
There are 3 different tyres in the Michelin 185 X 15 range, namely XAS & 2 X XVS & each is available in 3 different compounds A, B & C. So what are we talking about?
Last edited by Glyn M Ruck; May 23, 2023 at 03:19 AM.
The original XJ6 tyre was the Dunlop Sport ER70, which should have been a very good, even ground breaking tyre. Unfortunately, someone, probably an idiot in UK government, had the bright idea of making them in a new factory in the north-west where the geometric concept of the circle was not well understood; in fact, it was totally absent. In spite of or perhaps because of their lack of roundness, large numbers of these tyres managed to jump the factory fence and were offered to anyone who owned any sort of Jaguar at bargain prices. This was only one of Dunlop's misadventures of the time that ended in it being broken up by asset strippers. The tyre part of the business has passed a couple of upheavals since then and these days name is merely a brand. In Europe, it's owned by Goodyear, who have used it as a performance brand, and their various SportMaxx have been excellent summer tyres. However, that may be changing as they don't appear to have updated the range in the last year or so.
Another of Dunlop's misadventures was their short lived partnership with Pirelli, which resulted in them pouring money into a cash hole in Milan. After the disaster with the XJ6 tyres from Dunlop, Jaguar went to Pirelli in search of an alternative OE supplier. The result was the P5 fitted to the XJ6. One of those strange contradictions that arise in history.
