Author Topic: Spare tyre  (Read 1215 times)

TnTkr

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Re: Spare tyre
« Reply #15 on: June 05, 2020, 09:05:29 AM »
It is indeed designed to carry maximum five adults, but with htat maximum load it is far away from the nominal height. Even two kids (total about 50 kg) in the rear seat makes the rear of the car visibly lower. Spare wheel weights less, but is much more rear.

jazzaro

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Re: Spare tyre
« Reply #16 on: June 05, 2020, 09:42:31 AM »
Full size spare is adding weight and even adding it to very rear of the car, therefore I have doubts that it can lower the rear suspension visibly. Has anybody tried and measured it? The effect to the performance is easily calculated.

I often drive with a rear passenger and the trunk full. The car lowers, but there are no consequences for the handling. Performances are reduced, but the handling remains very very good even with full load at high speed, and I like it very much.
If you want to worsen the handling, put a set od Ecocontact6 or other soft tires; this car want tires with hard shoulders, I made a mistake replacing the OEM Dunlops with the Continental. Next time, Dunlop or Yokohama...

culzean

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Re: Spare tyre
« Reply #17 on: June 05, 2020, 09:44:47 AM »
On the other hand, a light alloy wheel could reduce the effect. What could be the lightest 15x6 or 16x6 alloy wheel for spare?

I have both steel wheels with winter tyres ( Nokian, great in snow ) and alloys with summer tyres and the steel wheels are lighter than the alloys - with alloys it is all about style - the cross section of the alloy has to be more than steel so no weight saving,  and I have never seen a steel rim crack or corrode under the tyre bead ( causing a slow leak ), which has happened on alloys. Alloys are a PITA for maintenance and having to get them refurbished every so often at no small cost ( diamond cut are the worst ),  with steel it is basically fit and forget ( with maybe a coat of Hammerite paint after many years ).
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

TnTkr

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Re: Spare tyre
« Reply #18 on: June 05, 2020, 09:53:12 AM »
I have both steel wheels with winter tyres ( Nokian, great in snow ) and alloys with summer tyres and the steel wheels are lighter than the alloys - with alloys it is all about style - the cross section of the alloy has to be more than steel so no weight saving,

This is interesting, thank you for this information. I have to dig this deeper.

In theory you should be able reduce weight with alloy but maybe the design is optimized for looks not for the strength. I wish there were pressed aluminium wheels (i.e. same construction as steel wheels) for Jazz. BMW had those in 90's and they were really light.

sparky Paul

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Re: Spare tyre
« Reply #19 on: June 05, 2020, 11:11:07 AM »
I would think that the suspension deflection from an additional 10-15Kg of a spare wheel would be barely measurable, let alone visible.

TnTkr

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Re: Spare tyre
« Reply #20 on: June 10, 2020, 09:05:29 AM »
I have both steel wheels with winter tyres ( Nokian, great in snow ) and alloys with summer tyres and the steel wheels are lighter than the alloys - with alloys it is all about style - the cross section of the alloy has to be more than steel so no weight saving,

This is interesting, thank you for this information. I have to dig this deeper.

In theory you should be able reduce weight with alloy but maybe the design is optimized for looks not for the strength. I wish there were pressed aluminium wheels (i.e. same construction as steel wheels) for Jazz. BMW had those in 90's and they were really light.

According to various sources from the internet Honda's 15x6 steel wheel weighs about 8,2 kg. Lightest same size (or 6,5) alloy wheels weighs less than 4 kg. Of course this is extreme and expensive, most alloys are around 7 kg.  The tyre itself weighs 7-8 kg. So there is possibility to save maximum 4 kg per wheel. Maybe not worthwhile regarding spare, but certainly interesting, although expensive.


Jocko

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Re: Spare tyre
« Reply #21 on: June 10, 2020, 09:31:37 AM »
Since I am carrying an extra 34 Kg round my waist I think my spare tyre will make a greater difference to my car's performance than the car's spare tyre!

Downsizer

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Re: Spare tyre
« Reply #22 on: June 10, 2020, 10:25:50 AM »
According to various sources from the internet Honda's 15x6 steel wheel weighs about 8,2 kg. Lightest same size (or 6,5) alloy wheels weighs less than 4 kg. Of course this is extreme and expensive, most alloys are around 7 kg.  The tyre itself weighs 7-8 kg. So there is possibility to save maximum 4 kg per wheel. Maybe not worthwhile regarding spare, but certainly interesting, although expensive.
Over 50 years ago I worked in a magnesium foundry, and among other things we cast magnesium wheels for racing cars.  I expect we charged a lot for them - they were more or less hand made.  We also made battery plates for torpedoes, magnesium-thorium alloy for helicopter gearboxes, powder for explosives, and containers for uranium rods for the Magnox power stations.  It's a versatile metal, and inflammable in some conditions.

TnTkr

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Re: Spare tyre
« Reply #23 on: June 10, 2020, 10:28:13 AM »
For anyone who might be interested, I went and weighted the Honda accessory alloy wheel JA1503 (made in Italy) https://clubjazz.org/forum/index.php?action=dlattach;topic=12042.0;attach=5911;image , and it had exactly the same 8,2 kg weight than the steel rim.
« Last Edit: June 10, 2020, 10:31:26 AM by TnTkr »

Jocko

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Re: Spare tyre
« Reply #24 on: June 10, 2020, 10:30:36 AM »
Magnesium powder was used for early photographic flashes and I remember our chemistry teacher burning a strip in class. We saw a green spot for rest of day. Elf and safety wouldn't allow that these days.

TnTkr

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Re: Spare tyre
« Reply #25 on: June 10, 2020, 10:32:45 AM »
Magnesium powder was used for early photographic flashes and I remember our chemistry teacher burning a strip in class. We saw a green spot for rest of day. Elf and safety wouldn't allow that these days.

As far as I know they still demonstrate burning magnesium strip in high school chemistry classes in Finland.

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