What tyre sizes are suitable for a Stag?

[MagicMatch]

Hi,
My Stag is a 1976 auto. I've noticed my speedo i reading a good 5mph too low and have been driving on the rev counter. At a show I attended last weekend a chat with a fellow member revealed I'm on the wrong size tyres. The car is currently in for servicing so I can't tell you what size that is.

I've tracked down two tyres that I'm told will fit factory alloys and be ok. Michelin XAS 175 HR14 and Blockley 185 HR14, but both are very expensive.

I've been searching the web for what seem to be close sizes, but I'm hampered by the fact that I don't know what I'm talking about!

Since I had my last Stag, profile measurements are now given and it's really throwing me out.
Blockley tell me their tyres are 185 with a profile of 80 (80 what?) and are 14 inch and will be ok.

Searching the web I have found a fair range of tyres offered by Black Circles who correctly identified my car by registration number and offered me a range of tyres but there are some differences in the sizes. Most are 185/80R14
Will these actually be ok? I'm chiefly concerned about getting an accurate speedo.
Many thanks.

[Lingen]

Black Circles is a good place to be looking. Blockley and Michelin are very expensive, so for years now I have used 195/70/14 tyres which are available in a good range of makes and prices.
I have gone for Dunlops, which are a reasonable price, and perform really well. That radius is so close to the original 185/80/14 that the speedo should hardly be affected. It was probably never all that accurate from the start. Have you checked it against a satnav? If it is unacceptably out for you, it is not too difficult to re-set it, although the mileage may not be spot-on.
Mike.

[jakesmig]

hands up anyone who has an accurate speedo?

To be fair, my Stag and Midget both have accurate speedos because they are digital and are programmed specifically to the wheels on the cars.

My Modern is, according to GPS instrumentaltion, 4mph out at 30, 6mph out at 60 and 8 mph out at 70. I've never had a modern with a 100% accurate speedo.

The profile of a tyre is a percentage of the width, ie 185/80/14 is 80% of 185mm = 148mm, a 14" rim is 355mm dia. therefore the wheel & tyre diameter should be 355 + 2x148 = 651mm or 25.6",
A 195/70/14 tyre would be 70% of 195 (136mm) therefore wheel and tyre diameter would be 355 + 2 x 136 = 627mm or 24.7".

These are the inflated unloaded diameters, the rolling radius of a loaded tyre is not the mathematical

Try the following for more information, they know the facts better than I.

https://www.tyresizecalculator.com/tyre-wheel-calculators/tire-size-calculator-tire-dimensions

Rgds

John.

[DJT]

hands up anyone who has an accurate speedo?

I do. To be fair though, it is an electronic version of the Stag Speedo, driven from a sensor on the back axle. It can be calibrated to any tyre/diff/gearbox combination and is spot on when measured against gps on a flat straight road.
311086E3-B42A-4E6D-8B51-62F314C08818.jpeg E4F39792-3260-4004-9EAB-E95B6501D883.jpeg
My modern reads about 2mph high across the range.

[stag8manod]

My speedo is spot on at 100k according to TomTom. Fitted with 195/70 Michelins on Stag mags, 3.45 diff, J Od and a speedo drive from a 2.5S saloon.
Both moderns, a Mazda 3 SP25 and a Ford Courier ute read 4K under
at 100k.
Cheers, Ian A

[Roy_S]

I went down the same route a few weeks back, see here.

https://www.socforum.com/forum/forum/stag-owners-club/soc-forum/821808-alloy-tyre-size

[MagicMatch]

Black Circles is a good place to be looking. Blockley and Michelin are very expensive, so for years now I have used 195/70/14 tyres which are available in a good range of makes and prices.
I have gone for Dunlops, which are a reasonable price, and perform really well. That radius is so close to the original 185/80/14 that the speedo should hardly be affected. It was probably never all that accurate from the start. Have you checked it against a satnav? If it is unacceptably out for you, it is not too difficult to re-set it, although the mileage may not be spot-on.
Mike.

Many thanks Mike. I'll check that size against what's fitted when I get the car back. I have checked the speed against a sat-nav, and it's way too low in these camera times. The vans are all over the place here.

[Phil Newton]

Hi, I have recently had a tapping noise from my engine, i suspected timing chains. When i removed the o/s cam cover the chain was slack, more worrying is i found swarf and the front cam follower broken and so loose i could nearly remove it !! Does anyone know what may have caused the follower to fail is this way ?? I live in Essex can anyone recommend a good mechanic with stag engine experience.
Many thanks
Phil. Sorry posted on wrong page

[Stag About Town]

For a start, all basic radial tyres without a different number included in the size marking are 80 series. This is the section height expressed as a percentage of the section width. Most makes never included the 80 in the size marking just the size and speed rating, eg. 175HR14. Early Stags mostly came with size 185 HR14 which is 80 series. Later models and I suspect your car being a 76, came with 175HR14 (also 80 series). If you have the original handbook it will be in there. Mine is a 77 auto and that came on 175HR14. If, as is most likely, your car came with 175HR14 you have two simple options. Stay with the original size or convert to 19570HR14 (70 series). This gives almost exactly the same rolling radius and diameter so the speedo will be correct as far as tyre size is concerned. OK for the Stag wheel size too. I went for 19570HR14 Khumo, a make fitted to most Kia and Hyundai cars today. Some opt for T speed rating which is probably ok but I prefer to stick to H to be on the safe side. I paid about £60-00 per tyre all in (inc fitting, valves, balance and vat) John

[SaintGeorge]

Hello, ive just fitted Uniroyal Rainexpert 195/70/14 after much research, they look great and through Blackcircles were about £80 each. IMG_6888.JPG IMG_6887.JPG

[MagicMatch]

I now have my Stag back from servicing and checked what tyres I have and the size. They are Firestone Multihawk 2 and the size is 175/80/R14, so it seems I'm not that far from the standard fitting. Stag About Town says that the original tyres will be 80 series, so this to me seems close enough (please feel free to advise me otherwise). I'm wondering whether I should have a look the cable that transmits the readings.
Thanks to everyone who posted on this thread.

[Stag About Town]

I now have my Stag back from servicing and checked what tyres I have and the size. They are Firestone Multihawk 2 and the size is 175/80/R14, so it seems I'm not that far from the standard fitting. Stag About Town says that the original tyres will be 80 series, so this to me seems close enough (please feel free to advise me otherwise). I'm wondering whether I should have a look the cable that transmits the readings.
Thanks to everyone who posted on this thread.

Your originals would most likely have been marked 175HR14 (which are 80 series even if not marked 80.) The H is the speed rating and the R is just for radial. At that time, crossply tyres were also around still. Your original make would have probably been Michelin or Avon. If your current tyres are marked 175/80R14 you will have a speed rating somewhere following that marking. Should be H but could be T which some members go for. They are suitable for cars capable of speeds up to 118mph but T did not exist in the seventies so all Stags came H rated. For those that comment on the legal limit, the tyre speed rating set by the manufacturer takes into account other factors like surge weight on acceleration and other stuff. Also the load index.