GT V8 original tyre size
-
- Posts: 21
- Joined: Thu Mar 02, 2023 6:04 am
- Forename: Rene
- Surname: Chinnery
- MGCC Member: Yes
GT V8 original tyre size
My MGB GT V8 original handbook states the tyre size to be 175HR x 14 - no mention of an aspect ratio to determine tyre diameter. The car has 185/70R 14 fitted. Does anyone know the original tyre aspect ratio or diameter / circumference please so I can work out of the tyres fitted have the same gearing and speedometer reading please?
- Paul Scott
- Posts: 333
- Joined: Mon Jan 08, 2018 8:48 pm
- Forename: Paul
- Surname: Scott
- MGCC Member: Yes
- Location: Milton Keynes
Re: GT V8 original tyre size
1975 MGB Roadster
Webguru for MGB Register
Webguru for MGB Register
Re: GT V8 original tyre size
The original size tyres, 175 x 14, will be full profile, which means they have the tallest side walls at about 82% of the width. So they would be classed as 175/82 (or 80 is close enough) x 14. There are dozens of tyre comparison sites out there, eg, https://tiresize.com/tyre-size-calculator/. Using that comparator shows that your 185/70 x 14 tyres are slightly smaller in circumference than the originals and will cause your speedo to over-read by about 4%. Whether you can actually buy the original size now I don't know.
Mike
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.
-
- Posts: 2
- Joined: Sun Mar 19, 2023 4:31 pm
- Forename: Gareth
- Surname: Evans
- MGCC Member: Yes
- MGOC Member: Yes
Re: GT V8 original tyre size
Even Halfords are saying this is an available size (175/80 R14), so any tyre specialist should have a better choiceBumpa wrote: ↑Tue Apr 11, 2023 9:41 am The original size tyres, 175 x 14, will be full profile, which means they have the tallest side walls at about 82% of the width. So they would be classed as 175/82 (or 80 is close enough) x 14. There are dozens of tyre comparison sites out there, eg, https://tiresize.com/tyre-size-calculator/. Using that comparator shows that your 185/70 x 14 tyres are slightly smaller in circumference than the originals and will cause your speedo to over-read by about 4%. Whether you can actually buy the original size now I don't know.
Re: GT V8 original tyre size
That's good that those tyres are still available. I said I didn't know because I don't need that size. My car runs on 195/65 x 15.
Mike
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.
1969 MGB GTV8 3.9 Conversion. Many classics have passed through my hands but the faithful BGT V8 is the last man standing.