Is it dangerous to have slightly different profile tyres on the same axle? I have a loan car which has 195/55/R15 on 3 wheels and one odd (the spare I think, it's not an alloy) on 195/60/R15s. The odd couple are on the rear of a fwd car. The tyre presssures were all over the shop, 2 front wheels on 38psi and one rear on 15 psi (the odd wheel) the other on the same axle was 46psi! Any idea what the correct pressures are for a primera? I've put them around 34 at the front and 30 at the rear (slightly warm). I assuming a previous driver saw the odd sized wheels and thought it would be sensible to even up the sizes by over inflating one and underinflating the other!
teabelly
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Looking at the MOT site, it would fail.
I don't know if it would be dangerous, but 3 points and a big fine?
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It sounds dangerous but would you get done? What about spacesaver tyres?
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As it would fail an MOT then I'm going to contact them tomorrow and see what they say. If they don't offer to sort out paying to replace the tyre with the correct one then there will be trouble :-)
teabelly
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Loan car from where???? I would have taken it straight back and told them to get me a car that was legal and safe!!!!
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Indeed, while some cars have different front to rear to sort out the handling, this gives a car that'll have different characteristics turning left and right.
And that is scary!
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It's dangerous, illegal, would fail MOT and likely invalidate insurance.
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As was said earlier, how would this be different from spacesaver wheels, which are usually very different, but, of course, are speed limited.
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Although I think the speed limit on the wheel on our Xantia is 70 mph.
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The spare on the Fiesta (new shape) looks just like a bog standard steel wheel just with a low speed-rated tyre.
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Mike Farrow
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My 51 reg transit tourneo came supplied with 195/65/16 alloys on the road wheels and a 195/70/15 steel spare. the rolling radius is apparently the same. MOT no problem I presume?
papho
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Looking at www.miata.net/garage/tirecalc.html shows that the spare is 0.9% smaller. Revs/mile 776 for 16" and 783 for the spare. If that is close enough, then OK. I wouldn't use the spare for very long on a driven wheel, as the diff will be 'working' the whole time. A 215/65-15 is just about right, at 0.1% error.
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papho - MOT no problem as long as spare is in the boot (not tested). Could be a problem if fitted.
www.motuk.co.uk/manual_410.htm
Reason for rejection
This inspection applies to
Tyres fitted to the road wheels only. The vehicle presenter should be informed when it is noticed that there is a defective tyre on a spare wheel.
1a. One tyre is of a different nominal size or aspect ratio to any other on the same axle.
b. Special lightweight or space saving wheels and tyres fitted as road wheels
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Sure it is not 195/55/R16 (16) on 3 wheels and 195/60/R15 on one, the spare? These would be a similar rolling ratio.
I had Vectra that had 205/55/16 alloys though the spare was 195/65/15 steel.
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Sure it is not 195/55/R16 (16) on 3 wheels and 195/60/R15 on one, the spare? These would be a similar rolling ratio. I had Vectra that had 205/55/16 alloys though the spare was 195/65/15 steel.
The spacesaver spare on my first Focus appeared to have a different rolling radius to the full size alloys. If the spare was fitted at the front it used to activate the traction control ~ the traction control obviously assumed that one of the front wheels was spinning. Unfortunately the handbook didn't tell you to switch off the traction control when fitting the spare at the front ~ you were left to work that one out for yourself!
--
L\'escargot.
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This reminds me of the good old days - Many years ago I solved the problem of my Austin 1100's inability to travel in a straight line by fitting a smaller 12" wheel from the Austin 1300 on to one side at the front. The combination of this and the normal 13" wheel on the other side corrected the problem and the car drove perfectly! I later discovered that one of the steering rack mountings had parted company from the subframe.
I used to be indecisive now I am not so sure
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If a spare is an odd size to the other wheels (including spacesavers) it must be used only to get you to a garage to get a new tyre fitted - extended use is an offence. A neighbour ran round on a spacesaver for at least three weeks and we have two tyre fitting outfits at the bottom of the street - IMO this info should be on the wheel along with all the other use instructions.
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Thanks for all the info gents, I have now had the opportunity to read the 'owners guide'. The only reference to the difference between the steel spare and the alloys is- "the wheel nuts of alloy wheels can only be used for the steel spare wheel for a short time (maximum two weeks)" !! Two weeks of 500 miles per day or two weeks of sitting on my drive I wonder??
The guide does not refer to the steel spare as a space saver because it IMHO it isnt, the tyre sizes are as I originally posted, ie they are both 195 width. The steel spare is, I guess a Ford financial saver, nothing less.
Apologies to teabelly for having rather hijacked his original thread.
papho
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Thanks for all the info gents, I have now had the opportunity to read the 'owners guide'. The only reference to the difference between the steel spare and the alloys is- "the wheel nuts of alloy wheels can only be used for the steel spare wheel for a short time (maximum two weeks)" !! Two weeks of 500 miles per day or two weeks of sitting on my drive I wonder??
It's probably a corrosion issue, so time is the only factor, not miles.
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Garage said get it sorted and they'd take it off the bill. I had a mobile tyre lot to check over the wheel that had been taken off and there was no puncture! There was one mark where it looks like they had driven over a drawing pin but it hadn't actually punctured the tyre....... so none the wiser as why someone took off a perfectly good tyre to replace it with the wrong sized spare...
teabelly
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