Why is rim size the only Imperial unit on an F1 car?

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strad
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Re: Why is rim size the only Imperial unit on an F1 car?

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Craigy
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Re: Why is rim size the only Imperial unit on an F1 car?

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I like bizarre units. I recently found out that in the UK, the railway has it's own unit for measurement of distance between bridges, using the unit "chains". It's still the way they work today. Bonkers.

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henry
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Re: Why is rim size the only Imperial unit on an F1 car?

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Craigy wrote:
10 Mar 2020, 07:12
I like bizarre units. I recently found out that in the UK, the railway has it's own unit for measurement of distance between bridges, using the unit "chains". It's still the way they work today. Bonkers.
It’s sort of metric. 10 chains is a furlong.

And a furlong by a chain is an acre. Easy peasy see.
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Just_a_fan
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Re: Why is rim size the only Imperial unit on an F1 car?

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Craigy wrote:
10 Mar 2020, 07:12
I like bizarre units. I recently found out that in the UK, the railway has it's own unit for measurement of distance between bridges, using the unit "chains". It's still the way they work today. Bonkers.
Chains are an old measurement not unique to the railways. Land surveying used chains. It was an actual chain with markers on it for subdivisions.

https://en.m.wikipedia.org/wiki/Chain_(unit)
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JordanMugen
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Re: Why is rim size the only Imperial unit on an F1 car?

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henry wrote:
10 Mar 2020, 11:03
It’s sort of metric. 10 chains is a furlong.
22 yards in a furlong, and 3 feet in a yard. Couldn't be easier. :wink:

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PlatinumZealot
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Re: Why is rim size the only Imperial unit on an F1 car?

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Car lengths. Is that imperial? Lol
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Just_a_fan
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Re: Why is rim size the only Imperial unit on an F1 car?

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JordanMugen wrote:
18 Mar 2020, 04:12
henry wrote:
10 Mar 2020, 11:03
It’s sort of metric. 10 chains is a furlong.
22 yards in a furlong, and 3 feet in a yard. Couldn't be easier. :wink:
220 yards in a furlong... :-"
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bill shoe
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Re: Why is rim size the only Imperial unit on an F1 car?

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I didn't see the actual answer to the thread title anywhere in this thread.

In the early days of cars and relatively modern wheels/tires, car makers were going in the direction of having custom sizes of wheels/tires for their cars. This would lock consumers into buying replacement wheels/tires (many back then due to state of roads and state of wheels/tires!) from the original car company or at least into buying very obscure and specialized sizes from independent sellers (which was not practical). So car companies were on their way to "tethering" high-margin replacement wheels/tires to the original cars.

The Tire and Rim Association was created in the U.S. to standardize sizes and specs for tires and wheels. For once the good guys won, and TRA was tremendously successful at bringing this standardization and sanity to the automotive industry. TRA standards and specs are still the bible today for any car company bringing a new vehicle model to market or introducing new wheel sizes for an existing model. Consumers can buy the same specs of replacement tires for their Ford or Toyota or VW.

I think the success of TRA in the U.S. led Euro and Asian companies to adopt this system, which also made additional sense as car export/import between continents became more common. So today, all automotive/tire companies "think" of tire sizes and specs in terms of old U.S. (TRA) units, even though the detailed Engineering drawings of tires and wheels are now of course in normal SI/metric. Just like how current F1 tires are made for 13-inch wheels, but the rules are spec'd in mm. All significant tire and car companies in the world are members of TRA.

So TRA (and no I have no connection to them) has saved the world truly vast amounts of money and headaches over the last 100+ years. One of humanity's most successful organizations that nobody has heard of.

http://www.us-tra.org/aboutTRA.html

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JordanMugen
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Re: Why is rim size the only Imperial unit on an F1 car?

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JordanMugen wrote:
27 Feb 2020, 22:30
Metric diameter wheels are extremely uncommon, and if you have the misfortune to own a car with metric wheels the tyres are horribly expensive. Most owners will convert to standard imperial wheels.
bill shoe wrote:
18 Mar 2020, 16:05
I didn't see the actual answer to the thread title anywhere in this thread.

TRA standards and specs are still the bible today for any car company bringing a new vehicle model to market or introducing new wheel sizes for an existing model. Consumers can buy the same specs of replacement tires for their Ford or Toyota or VW.
How did the Michelin metric TRX tyre sizes fit into this TRA scheme? For example, Ferrari 308 GTB with OEM rear tyre size of 220/55R390 (approximately 15.35" wheel diameter).

Michein says:
The 1970’s saw the beginning of collective car safety awareness. Wearing seatbelts became compulsory and speed limits were introduced on roads and motorways in numerous countries. For tyres, this led to improved grip, more precise steering, as well as enhanced stability and comfort, thus avoiding excessive driver fatigue on long journeys. This decade witnessed the advent of high performance vehicles capable of covering hundreds of miles in one go, with exceptional levels of safety and comfort, such as the BMW 7 series (1977) or 5 and 3 series which followed the same trend, Citroën CX 2400 GTI (1977), 604 (1975), Renault 30, etc... Sports cars also benefited from this progress. Examples were the Ferrari 308 GTS and GTB (1977) and 512 BB (1976), Alpine A310 V6 (1976), Renault 5 Turbo (1979), BMW M 635 (1984), Peugeot 205 Turbo16 (1985), etc... All these cars (and many others) had the Michelin TRX fitted as original equipment, and still can today, with a tyre true to that era, but manufactured using today’s techniques and materials.
https://classic.michelin.com/en/Classic-Tyre-range/TRX

bill shoe
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Re: Why is rim size the only Imperial unit on an F1 car?

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I think a few euro tire companies tried metric sizes, mostly during the 70's. This was a logical thing to try at a time when the metric system was taking over the last holdout countries on earth. But apparently there was no critical-mass agreement about the metric standardization via an organization like TRA. Ultimately, the standardization of sizes and specs was more important than what units were used, so TRA and the older units "won".

Of course, the TRA standard for tires size designation (ex: 225/50-16) is a deliciously awkward blend of mm, %, and inch.

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Big Tea
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Re: Why is rim size the only Imperial unit on an F1 car?

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Craigy wrote:
10 Mar 2020, 07:12
I like bizarre units. I recently found out that in the UK, the railway has it's own unit for measurement of distance between bridges, using the unit "chains". It's still the way they work today. Bonkers.
Horse races are still measured in furlongs one eight of a mile. From the original measurement of a furrow long or the standard length of a field border to border.
When arguing with a fool, be sure the other person is not doing the same thing.

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JordanMugen
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Re: Why is rim size the only Imperial unit on an F1 car?

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bill shoe wrote:
20 Mar 2020, 17:29
I think a few euro tire companies tried metric sizes, mostly during the 70's.
Thanks for the post!

TRX tyres sure are superb and wonderfully interesting! :D

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The TRX tyres require the shallow rim on the right:Image