Car tyre aspect rat...
 

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[Closed] Car tyre aspect ratio

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I’m having a nightmare with a car repair at the moment (Arnold Clark you bunch of muppets) a very small part of the repair included 2 new front tyres. I asked them to match the back but they haven’t, on the back I have 175/65 R15 84T and they have put 175/75 R15 84T on the front. Will the extra 10mm aspect ratio make a difference? My car has ABS which a quick read would suggest could cause problems.


 
Posted : 17/01/2019 10:49 am
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Assuming you have everything correct with those numbers, the front tyres are now bigger than the rear. This will affect your actual speed vs displayed speed assuming the correct tyre size for your vehicle is the 65 on R15 (you will be going faster than you think). if it is the rear ones that are actually the wrong ones for your vehicle, (too small) it won't affect your speedo.

In either case I would think that having different sizes like this on a car not designed to take that might affect the handling to some extent


 
Posted : 17/01/2019 10:57 am
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I would get them to change as even if abs ok speedo will be out (and insurance maybe not happy) and I believe aspect is a percentage of width and not mm


 
Posted : 17/01/2019 10:57 am
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I'd reject if that's not the OE size (check the rears weren't wrong!). Might get tyre rub on lock with a taller tyre on top of the additional issues.

(If rears were non-standard they may argue they can't fir non-standard tyre sizes for warranty reasons, I guess)


 
Posted : 17/01/2019 11:01 am
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https://www.willtheyfit.com

Will tell you exactly what the real difference is.

But a call to a main dealer will tell you what size should be on there. And tell the muppets to fit those (if they haven’t)


 
Posted : 17/01/2019 11:01 am
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The tyres are 17.5 mm taller - get them to put the size on you requested.
And yes they are muppets - an organisation like Ryanair where they have the same ****less culture from bottom to top. An excellent example of leadership though.


 
Posted : 17/01/2019 11:04 am
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Is the question really just "will this work"? They've fitted the wrong tyres, tell them to put on the correct ones

EDIT:

And yes they are muppets – an organisation like Ryanair where they have the same ****less culture from bottom to top.

TBF, I bet Ryanair have the right sized tyres on their planes


 
Posted : 17/01/2019 11:05 am
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Erm. That's quite a big change.

The number is percentage of width, not mm.
So the tyre width is 175 & the 65 or 75 refers to the sidewall height as a percentage of the width.

So 175/65 is a sidewall height of (175*0.65) 113.75
and 175/75 is a sidewall height of (175*0.75) 131.25

a difference of 17.5mm...the car manual should tell you what alternative tyre/wheel sizes are acceptable.
I'd say with that variation, as mentioned above you may be on thin ice with your insurance company.


 
Posted : 17/01/2019 11:05 am
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Couldn’t you just do some burnouts and take a bit of tread off them?

🤣👍


 
Posted : 17/01/2019 11:07 am
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I thought it was all about slackening the head angle around here?


 
Posted : 17/01/2019 11:18 am
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Head angle will be slacker, so it will make the car more stable and less twitchy 😉


 
Posted : 17/01/2019 11:27 am
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Yes, but the reach will be smaller and the stack will be higher so you might have to move the seat back and sit on a cushion to see over the dash.

But, seriously, as above, have them fit the proper tyres that you requested.


 
Posted : 17/01/2019 11:31 am
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What size are the tyres supposed to be? Are the rears correct for the car, or have you (inexplicably) changed them for something smaller? If it's the latter, they won't/shoudn't knowingly supply tyres which aren't meant to go on the car.


 
Posted : 17/01/2019 11:51 am
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I think they may have put on the proper size tyres when it was in the factory, i put 225/45 r17 on my car due to the fact much more choice and far better deals rather than the 55 profile meant for the car, can't believe they would try and cheat


 
Posted : 17/01/2019 1:32 pm
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Thanks all, the rear tyres are the correct size for the car.


 
Posted : 17/01/2019 1:35 pm
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can’t believe they would try and cheat

Did you not notice the name of the garage in question?


 
Posted : 17/01/2019 1:44 pm
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can’t believe they would try and cheat

I could.
Sorry.
I would expect it.

Sadly, they sell the cheapest cars around.


 
Posted : 17/01/2019 1:54 pm
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There are all sorts of problems with switching tyre aspect ratios. You may also find insurance is invalid.

While Ar**hole Clark have it back to fix it properly, get them to take their sticker out of the back window. I don't know what those things are made from, but it must be heavier than anything else known to man because whenever I'm behind a car with one, they're invariably going veeery slooow.


 
Posted : 17/01/2019 1:56 pm
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I'm not surprised Arnold Clark really are a bunch of ****less muppets.

There is no way they should be fitting the wrong sized tyres to your car.

Tell them to do one and fit the correct tyre size. Threaten to report them to the Motor Ombudsman (yes its a thing) if they refuse


 
Posted : 17/01/2019 2:00 pm

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