Tyre Question 225 to 205

Merty

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Hello Guys, Just a quick one,

I need to change my tyres at the front and i have 225 55 16 - 99 on them atm but a friend of mine has 205 55 16 -91 on them - would i be able to fit his ones one mine, would it take any effect ?
 

theogeor

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You should not as you will have 22mm (almost an inch) difference in the diameter of the tyre and that can pottentially affect a lot of the characteristics of the car

Regards

Theo
 

jonthetourist

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You should not as you will have 22mm (almost an inch) difference in the diameter of the tyre and that can pottentially affect a lot of the characteristics of the car

Regards

Theo
Can I just check this? I believed the 225 / 205 was a measurement of width, and the diameter = the wheel size plus tyre profile, which is unchanged.

Jon
 

E55BOF

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The '55' is expressed as a percentage of the tyre width, hence the difference
 

grumpyoldgit

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As the aspect ratio is going to be less, i.e. 55% of 205 is smaller than 55% of 225, it will affect the overall diameter of the tyre slightly and will result in your speedo reading faster than the speed at which your are actually travelling.
Why do you want to fit narrower tyres?

Tyre Size Calculator
http://www.etyres.co.uk/tyre-size-calculator
 
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Sambo

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I fitted narrower tyres once (225 to 205 but on 17"s) and it increased the fuel consumption without a noticeable compromise to anything else
 

theogeor

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I fitted narrower tyres once (225 to 205 but on 17"s) and it increased the fuel consumption without a noticeable compromise to anything else
Did you keep the same profile ?? Personally I would not do that unless I had the car been fully geo adjusted by someone who knew what he was doing and there are not that many who would know what you need to do.


On the specific question we had at the begining if Merty needs narrower tyres then 205/60R16 should be the replacement as they only have 2mm diameter .

Theo
 

jonthetourist

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On the specific question we had at the begining if Merty needs narrower tyres then 205/60R16 should be the replacement as they only have 2mm diameter .

Theo
Thanks for the clarification above - I hadn't realised the profile number was a percentage.

Presumably 2mm on diameter is not material, as 1mm of tyre wear creates that change?

Jon

PS I have 225 x 55s too, hence my interest.
 

Rory

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It should also be pointed out that you really ought to run this by your insurance company.
 

theogeor

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Presumably 2mm on diameter is not material, as 1mm of tyre wear creates that change?

Jon

PS I have 225 x 55s too, hence my interest.
Yes 2mm difference is fine and should not be a problem at all. Saying that check the alloy width to make sure they are not too big for 205 tyres. Do you know the size of them

Never as straight forward as it looks

Theo
 
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Merty

Merty

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thanks for the replies guys, i will have to have a look now as it some good feedback .
 

markjay

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Which model car do you have and what size were the original factory-fitted wheels and tyres? I think this should be the starting point for the various calculations, and not the tyres you have on the car now and which may or may not be the correct size for the vehicle.

You should be fine fitting any tyre size that was originally speficed for you car either as original size or as an option, assuming you have the right-sized wheels for these tyres (the owners manual will show both).

On another note your current tyres seem to be built for heavier load (99) than the narrow tyres you intend to use (91). Again, difficult to tell which of the two is correct for your vehicle without checking the owner's mamual.
 

markjay

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I fitted narrower tyres once (225 to 205 but on 17"s) and it increased the fuel consumption without a noticeable compromise to anything else
Surely you mean 'decreased..'?

It would be odd for narrow tyres to consume more fuel than wide ones, unless the tyre pressures were wrong?
 

gIzzE

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changing all the tyres will just change the gearing, but don't put smaller tyres on the front, you will throw the DSC etc. way out.


Also, narrower tyres will increase mpg, less rolling resistance, if you lost mpg then it was either a tyre that was not as good rolling resistance wise, or maybe it was you didn't increase the profile and thus the car was higher geared so sat doing more revs at a given speed.
 

grober

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I would be more concerned about the change in load characteristics as has been said. You could compensate by increasing the tyre inflation pressure as any tyre's load bearing capability is directly related to its pressure up to certain limits but this would also effect the cars ride. Why would you want to change from the recommended standard size-- any saving by a reduction in size could be equalled by purchase of a cheaper make of tyre of the correct size which would be the better way to go.
 

brandonmorris

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To be fair you don't really want to for non recommended standard size. You may save some money their but at the end it won't work out for you well.
 

mct_cars

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Surely you mean 'decreased..'?

It would be odd for narrow tyres to consume more fuel than wide ones, unless the tyre pressures were wrong?
My guess is the odometer measured more miles than actually travelled with smaller tyres.....
 

twolamps

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tyre size

Hello... could anybody tell me if i could move up from 205/55/16, too 225/55/16 on my 2006 c200 cdi. Thankyou..
 

twolamps

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Hello... could anybody tell me if i could move up from 205/55/16, too 225/55/16 on my 2006 c200 cdi. Thankyou..
Iv been given a set of new 225's i only do 3000 mile a year in my car.. so the mpg is not very important.. i would just like too know if they would be ok on my 2006 c200 cdi..
 
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gIzzE

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Try it, it may run on the arches are you going bigger, speedo will be out too.

You really want 225/50/16s if going wider.

But give it a go.
 

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