Best Answer Cooperman , 23 August 2015 - 03:57 PM
A 165/70 indicates that the tyre wall height is 70% of the width. The 70 is a percentage and is known as the 'aspect ratio'. So a 165/60 x 12 will have almost the same rolling radius (that's the dimension from the wheel centre to the outside diameter of the tyre) as a 145/70 x 12.
A 12" wheel can have either of the above. Maximum wheel widths are a completely different issue.
On my road car I have a 275/40 x 19, so the height of the tyre wall is 40% of 275 mm.
To get the nominal rolling radius multiply the tyre width by the aspect ratio and add 50% of the wheel diameter, converted to mm by multiplying by 25.4.
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Camshaft & Stage Two Head
Posted 22 August 2015 - 04:24 PM
At the moment I have 165/60/12 yoko tyres on my Ultralites 12x5J wheels. I note on the FAQ from Guessworks that Falken make a 165/70/12 to suit this wheel size. Has anyone fitted these and are there any problems either with the rear radius arms (I have S type drums) or the front wings rubbing. I have Hi Lows fitted all round so I can raise the suspension if necessary.
For those wondering why? it's 'because I need a softer ride now I'm in my dotage. Bring back Hydrolastic for pensioners. Lol
Uncle Cooperman, Voted Mr TMF 2011
Posted 22 August 2015 - 04:42 PM
They will not fit because the rolling radius is too big. Also they would hit the inner front wheel arches on full lock.
If you want a deeper sidewall to further improve suspension compliance you need to go to 10" wheels, which requires the 7.5" brakes. Then you can run a 165/70 x 10 or a 145/80 x 10.
Camshaft & Stage Two Head
Posted 22 August 2015 - 06:11 PM
I thought that then I found this old post by Guessworks re tyres available.
http://www.theminifo...eel-rim-widths/
I respect both posters but am now in a quandry. This car, an '89 City E had 145/70/12 tyres as standard so the rolling radius should be OK but as you say the lock could or is the problem. Perhaps it's the offset of the Ultralites that's going to screw it all up.
Still like to hear from someone who maybe has tried this.
One Carb Or Two?
Posted 22 August 2015 - 06:19 PM
Put the tyre sizes in a calculator to compare the diameter. http://www.tyresizec...tire-dimensions
I've had 155/70x12 tyres on the Midas in the past, and also had them on a Mini too. 165/70 is pushing it though.
You'd probably be better focusing on the suspension. For example most adjustable (if not all) hi lows have a larger diameter surface acting on the rubber doughnut, which I'm lead to believe increases the effective spring rate.
Edited by Artstu, 22 August 2015 - 06:34 PM.
Uncle Cooperman, Voted Mr TMF 2011
Posted 22 August 2015 - 06:47 PM
I also had 155/70 x 12 on a 1990 Cooper because we had to use Colway Tyres for a specific rally. They did hit the inner wheel arch and screwed up the speedo. Not ideal I have to say and much better with 165/60 x 12.
Camshaft & Stage Two Head
Posted 22 August 2015 - 07:37 PM
Put the tyre sizes in a calculator to compare the diameter. http://www.tyresizec...tire-dimensions
I've had 155/70x12 tyres on the Midas in the past, and also had them on a Mini too. 165/70 is pushing it though.
You'd probably be better focusing on the suspension. For example most adjustable (if not all) hi lows have a larger diameter surface acting on the rubber doughnut, which I'm lead to believe increases the effective spring rate.
Aaahh, I didn't realise that the wider the tyre the bigger in diameter it became. I always thought that for the same profile and wheel size the diameter of the tyre remained constant.
I've gone back to look at the link I put in from Guessworks re. tyres suitable for mini rims. This paragraph in particular:
'Falken FK-07E 165/70R10 Rim Width 4.00" to 5.50"
Falken FK-07U 165/70R12 Rim Width 4.00" to 5.50"
Falken FK-06G 165/60R12 Rim Width 4.50" to 6.00" '
Perhaps the suffixes E, U and G refer to tyre height or overall diameter. I tried looking on the Falken website but couldn't find any info, and Google couldn't help
Uncle Cooperman, Voted Mr TMF 2011
Posted 23 August 2015 - 03:57 PM Best Answer
A 165/70 indicates that the tyre wall height is 70% of the width. The 70 is a percentage and is known as the 'aspect ratio'. So a 165/60 x 12 will have almost the same rolling radius (that's the dimension from the wheel centre to the outside diameter of the tyre) as a 145/70 x 12.
A 12" wheel can have either of the above. Maximum wheel widths are a completely different issue.
On my road car I have a 275/40 x 19, so the height of the tyre wall is 40% of 275 mm.
To get the nominal rolling radius multiply the tyre width by the aspect ratio and add 50% of the wheel diameter, converted to mm by multiplying by 25.4.
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