I was told the same when I was learning all the laws in college, but when placed next to a normal road wheel it was smaller. I am told this is normal for many vehicles (4x4s in particular). Is possible that they are cheapo replacement space savers as the original was missing. Wouldn't really surprise me.
Tyre sizes
- Thread starter ragsyrandell
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sas1810
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On the sizes you have, you have a difference of -3.34% on the front. IE: when your rears are doing 30, your fronts are doing 29.
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Whilst only minimal, that would screw the Centre Diff no doubt as the poor thing is trying to differentiate the axle speeds all the time!!
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It's certainly NOT an Mot failure as long as both sizes are appropriate to the vehicle (load/speed index). It's only mixing on the same axle that's a failure.
I can't see that it's illegal anywhere, particularly in Germany, as a number of Porsche models have had wider rear tyres than front.
Since "space-saver" spares are legal in the UK, at least to "get you home", it cannot matter if the spare is a different size to the running tyres.
Cars as common as Avantgarde model (and maybe others too) Merc C Class's have different tyre sizes as standard. One has 205/55/16 front, 225/50/16 rear.
I can't see that it's illegal anywhere, particularly in Germany, as a number of Porsche models have had wider rear tyres than front.
Since "space-saver" spares are legal in the UK, at least to "get you home", it cannot matter if the spare is a different size to the running tyres.
Cars as common as Avantgarde model (and maybe others too) Merc C Class's have different tyre sizes as standard. One has 205/55/16 front, 225/50/16 rear.
Grit Valve
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As far as I am aware all space saving wheels that were made with the cars are of the same Circumference and as to a steering axel I think other laws applie I don't know the in and outs ??
sas1810
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Even though they are different sizes, the rolling circumference is the same. I worked for merc for 12 years and always asked the same question. They proved it with a chalk line test.
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Whilst there have indeed been models designed to have different sizes by axle...that is by design, the vehicle was designed and tested to have such...so yes, entirely legal...
But we are on about a spare space saver...I am sure it would have to match the original fitment rolling circumference on the vehicle else it would be wholly dangerous...
But then again, as you say it is just an 'Emergency' tyre to get to you home, so maybe the law reflects this, as long as it isn't used for a protracted period of time and you can prove you re indeed heading home following the incident!
sas1810
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And have you seen the cost of those space saver tyres? Approximately 3 times more than a new normal tyre.
I wouldn't like to have it fitted for long. Get a new tyre ASAP!
But going back to the original post, I agree with Ant. Sounds like the vcu is close to being worn out.
I wouldn't like to have it fitted for long. Get a new tyre ASAP!
But going back to the original post, I agree with Ant. Sounds like the vcu is close to being worn out.
On something like an Elise, it'd require having two space savers for front and rear. You're supposed to hobble along at reduced speed until you get home.
loudandproud205
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Space save is designed for a non driven axel, meant for the front of my MR2 as it would be an Elise.
Yet on the like of a Civic its meant to be run on the rear.
This is to save the diff as rolling resistance is different, but rolling radius is the same.
I had to use my space saver to get me 30 miles home and it was horrid and really do not exceed what the speed ratio says nothing I would want to recommend to anyone.
You will find that often on RWD cars the space saver won't fit on the rear.
Yet on the like of a Civic its meant to be run on the rear.
This is to save the diff as rolling resistance is different, but rolling radius is the same.
I had to use my space saver to get me 30 miles home and it was horrid and really do not exceed what the speed ratio says nothing I would want to recommend to anyone.
You will find that often on RWD cars the space saver won't fit on the rear.
offroadmad
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New cars dont even come with spacesavers anymore, now you get a puncture repair kit ( which are a complete waste of time & very rarely work ) keeps me busy tho cos im recovering them
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New cars dont even come with spacesavers anymore, now you get a puncture repair kit ( which are a complete waste of time & very rarely work ) keeps me busy tho cos im recovering them
+1
Do wonder however, how long until the main Motoring organisations decide they have to charge for "Puncture, no spare" Recoveries - why should they pick up the tab just so the manufacturers can save £100 per car?
offroadmad
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Agreed, apparently the manufacturers get the backing because it saves weight therefore reduces emissions sod the poor peeps stuck in a dangerous location without even a temporary spare to get them home, tbh i get called out to perfectly fit & able individuals to fit theyre spare for them as they dont kno how to do it,
offroadmad
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How the hell are theses idiots going to operate a puncture repair kit i ask myself !!!
Sounds familiar, like directional and non-directional tyres. You can't have a mix on driven axles, which means that if you have directionals all round and get a puncher on a driven axle and you have a non-directional spare, you need to start juggling around with tyres on the road side. Although when it comes to the 4x4 world, you're fooked.
StuckAgainSteve
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And have you seen the cost of those space saver tyres? Approximately 3 times more than a new normal tyre.
I wouldn't like to have it fitted for long. Get a new tyre ASAP!
But going back to the original post, I agree with Ant. Sounds like the vcu is close to being worn out.
Having mismatched front to rear sizes will overheat and kill the VCU as well as put tremendous stress on the props and diffs as the VCU will try to lock then cause tyre scrub.
