It is the XVS-P that is being discussed
This link shows all the good 185R15 tyres that you would consider for an XKE. https://www.longstonetyres.co.uk/tyres/185-15.html If you click on a tyre then it will give you all sorts of extra details about the tyre. such as heighth and width.
This link shows the 185/70VR15 tyres https://www.longstonetyres.co.uk/tyres/185-70-15.html
in theory the width of a 185/70R15 should be about the same as a 185VR15 (give or take a little. you will also notice differences between brands of tyre),
but the heighth will be approximately 10% of 185mm smaller in radius. also as you start getting lower like this then the tread is often a little wider in relation to the section width. But that is not such a great issue, if you stick with period tyres, but as you get more modern and lower it becomes more of an issue.
However 185/70R15 is totally wrong for an e-type. I know some of my competitors recomend it, but they are wrong.
205/70VR15 this page shows all the tyres we would sell in this size. https://www.longstonetyres.co.uk/tyres/205-70-15.html again click on a tyre it will show you the distention, which again vary from brand to brand. However 70% of 205mm is 143.5mm is about the same as 80% of 185mm = 148mm (ie not 70% of 185mm). which amounts to about the same diameter of tyre as the original 64.0_15 Dunlop RS5 which was 683mm when Dunlop still made it.
On this film it shows you all the tyres that we recomend https://www.youtube.com/watch?v=cioJAe2t8F4&list=PLORxf0xWk2NAz0J53D0dlFGi8rWwUOHYj&index=3 you can see the differences in tread width, and see the tyres in tthe flesh. But if you want to get yoour hands on them come and see us or arrange t o meet us at a VSCC race meeting.
205/70 tyres are over tyreing the car, which is why they didn’t fit them to the e-type in 1968 when it came out but waited until they fitted powersteering. there is a phenomena now where people are keen to fit a 205/65 or a 215/65 tyre or something of that ilk, because it is cheaper. The feeling that it is better is understandable, because of the perception that a modern tyre is better, which in some ways is true, but not for an e-type. a modern tyre suits different geometry. People then buy a new set of wheels, because you need a wider wheel to fit the lower profile tyre, which does cost less but will spoil your handling.
Of course because you are fitting a low profile tyre, you cannot use an inner tube. so you need a tubeless wire wheel. All cars that fitted wire wheels need inner tubes. I have seen too many failed tubeless wire wheels to trust them. Any tyre a discerning driver would want to fit to these cars would not be less than 70% profile.
It is a misguided rout to go down. Yes they are not cheap, but there are some great tyres in the right size for these cars. what you don’t want is to set yourself off down the rout of modifying you car to suit a modification that you did to make amends for another modification you did etc. etc…