Tyre Size

[Chrisalis888]

Hi there,

happy owner of a beautifully rebuilt SII FHC, but tyres are a wee bit cracked and elderly. Somewhat like my first wife I believe.....

Am looking at the options, and although I would like wider tryes for grip and visual appeal, steering wheel wrestling whilst parking (due to the absence of power steering) suggests I follow Longstone Tyres advice. Their website recommends a Michelin, the 180 15 XAS. They are also 'unkeen' on the notably cheaper Vredestein Sprint Classic, which has transformed my MGA.

Would love to hear from those who have gone either 205 or 180 and learn if there has been any notable change to the ride, driving characteristics and steering wheel input forces.

Thanks all and I hope to meet you somewhere this year.

Managed to get a pic in.

[acbautomotive]

Chris, prior to my restoration my E was running on 5J wires with 185/15 rubber, I decided to change these for MWS 6.5J wires with 205/65/15 radials which really improved the look of the car and did not make it look so long and thin (in my opinion)
Whilst the slow speed steering is obviously heavier than with skinny 185 cross plies, the tracking, road holding, ride comfort and steering response more than makes up for the slightly heavier parking speed steering.
When it came to select tyres for the new rims I had already exceeded my project budget (and some) instead of buying period tyres, I researched alternatives that had an older looking block tread pattern, a correct load and speed rating and an affordable price. I selected Michelin Pilot HX 205/65/15 MXV3A which were used on various OE fitments around 1999/2000, I found a number of these tyres that were unused and still on their steel rims having spent their life as a spare stored in the boot of the car in a cool dark environment, I selected a V rating up to 149MPH but did see some with W rating 168MPH. A set of 5 of these were obtained for less than £200.
This was one of the few examples of inexpensive E Type ownership.
Tony

[Chrisalis888]

Thanks Tony, a comprehensive and very helpful answer, concur re the skinny look of my originals, and am now hunting for a solution as your advice.

Very much appreciated, Chris

[Art1012]

Hi Chris,
I thoroughly agree with Tony's comments that modern wider tyres are much better ( I have 215/65/15 on my car with the MWS wheels Aston martin configuration having a larger hub / rim offset) If you need to ask about this set up please talk to Ken Jenkins, the clubs technical expert who advised me when I changed fro the skinny 185's.

However you need to think about the diameter and rolling radius of the original specification Tyres in order to keep your speedometer reading the correct speed. The original Dunlop SP tyres and the Avon Turbo tyres were 185 / 80 / 15, which gave them a outer Tyre diameter of approx 26.5 inches This is worked out by taking the rim diameter and adding twice the Tyre profile of 80%
(Rim 15" x 25.4= 381 mm plus twice (185x80%) 0r 148x2=296) So 381+296 =677 mm or 26.6 inches.

Your proposed Tyre size of 205/65/15 will result in a Tyre diameter of 25.5 inches (647 mm) 1 inch less than required. This may not sound significant, but translate this diameter difference into rolling radius and your rolling radius will be 3 inches less than the original spec which puts your speedometer out by around 12%. (slow)
What you need in order to maintain the correct rolling radius is a 205/70/15 Tyre profile which puts the rolling radius spot on at 26.5 inches. This is the Tyre which was fitted to late series 2 and all series 3 E-types.
I chose Dunlop SP Blue Response tyres as they are an excellent Tyre and look the part , having Dunlop SP embossed on the sidewalls same as the original tyres.
Hope this helps,
Art1012

[acbautomotive]

I am sorry that I do not concur with your 12% speedo error,

Tyre size........Diameter.......Rolling Radius....Circumference...Speedo Error
185/80/15.......677..............338..................2126................0
205/70/15.......668..............334..................2098................1.35%
205/65/15.......647..............323..................2034................4.5%
215/65/15.......660..............330..................2075................2.5%

Please could you correct me
Tony