Help understanding tires sizes for stock Ford Festiva

[steve s]

I read on this forum that "165/70 12's" were the standard factory tire on the Ford Festiva.

I've usually had 155 R12's on my stock Ford Festiva. I understand that the middle number (e.g. 70 above) pertains to the aspect ratio (height as a percentage of tread width) and thus for a given tread width (e.g. 165 or 155), the bigger the middle number, the taller the tire.

As far as I know no aspect ratio is printed on most of the 155 R12 tires I've purchased in the past.

What is the typical aspect ratio of a 155 R 12 tire that is sold to be used on a Ford Festiva?

What is the range of aspect ratio numbers that will work well on a 155-width 12" tire for a stock Ford Festiva?

How about for 165-width?

What is the aspect ratio of a 155R12 tire that will give the same outer wheel diameter (i.e. same speedometer calibration) as the 165-70-12 tire that the car was (apparently) originally sold with?

Not that I'm all that worried about the speedo calibration. The car sometimes carries fairly heavy loads and I don't want something that will rub, but better ground clearance is always a plus. My experience today is that I call up a tire dealer and they tell me there's no such thing as a 155R12, I need to know what the middle number should be before they can help me... I go out and look at tires on the car and they just say "155R12"....

Help! Thanks...

Steve S

[ryanprins13]

Help understanding tires sizes for stock Ford Festiva

The 155's are always 80 aspect ratio unless otherwise stated on the tire. I have them now and they are too tall and wobbly for my liking. The 145/80's handle much nicer. They are very close to stock circumference. Its a noticeable difference in acceleration with the 155's being slower. They are 3% bigger around. I have never tried the 165/70's although i would like to.

Probably should have asked all your questions in one post instead of 10 though.

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[bhazard]

145R12 was the original size for stock 4 inch wide steelies.

165/70R12 was the optional size for the 4.5 inch wide steelies and alloys.

[F3BZ]

around here the 155 seemed to be the standard stocked size back when you still walk in and get them from any tire store. maybe another more popular car (metro?) used 155 12s? i had to use tirerack to get the original 165s

[cav5k]

I've ALWAYS used 155/80/12's (155/R12)

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[ryanprins13]

Can anyone report on how well the 165 12's work or compare to the 145's as far as handling and all that?


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[drddan]

Ya'll keep forgetting the middle number, and is very important when selecting tires. Most of my tires on 12 inch rims are 155/80/12. Lets use that for an example.
The 1st number is width in millimeters 155=155 mm.
The 2nd number, in this case 80, is the height in percentage of the width 155 mm x.80 %=124mm.This is what makes tire diameter, smaller or larger.
The 3rd number is the wheel diameter it fits on

Here is a tire calculator you can put different tire sizes in to compare the diameters of different tires. Like a 175/45/14 tire to a 155/80/12 or155/70/12 tire, and find a diameter that is close to stock

https://tiresize.com/comparison/

[ryanprins13]

Help understanding tires sizes for stock Ford Festiva

Ya'll keep forgetting the middle number, and is very important when selecting tires. Most of my tires on 12 inch rims are 155/80/12. Lets use that for an example.
The 1st number is width in millimeters 155=155 mm.
The 2nd number, in this case 80, is the height in percentage of the width 155 mm x.80 %=124mm.This is what makes tire diameter, smaller or larger.
The 3rd number is the wheel diameter it fits on

Here is a tire calculator you can put different tire sizes in to compare the diameters of different tires. Like a 175/45/14 tire to a 155/80/12 or155/70/12 tire, and find a diameter that is close to stock

https://tiresize.com/comparison/

We know, but were lazy. In 12 inch rim size there arent any different aspect ratios available as far as i know. You cant get a 145/70 or a 155/70. They only come in the 80's or the 165/70.
Thanks for the link though! I just did it all out by hand a month ago for all the different sizes, lol.