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HI!!

Ok so this might be a straight forward answer but I wanted to ask you guys rather than being face to face with someone in a garage lol

i have just been given a set of wheels (taken from another astra j so I know they fit) but they currently have slicks on. So here is my question.

I have an astra SRi 1.6 with standard 17 inch wheels with 215/50/R17 tyres

I want to put on my new(ish) 18 inch wheels but what tyre size to I put on that will fit?

Sorry if it's a silly question :)
 

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Im not sure on the 18s but Iirc you need to change the tyre size in the ipc to keep the speedo right , i thought there was a configurator for tyre sizes on here somewhere tho


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AON - Administrator
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You say that you know they will fit because they are off a J but the J uses two different wheel configurations so that isn't necessarily true. What engine did the other car have and is it a 3 or 5 door?

Look on this page here for tyre sizes http://www.wheel-size.com/size/opel/astra/2015/ Tyre size is in the first column. In the third column is PCD, this needs to match between your car and the car they have come off
 

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You say that you know they will fit because they are off a J but the J uses two different wheel configurations so that isn't necessarily true. What engine did the other car have and is it a 3 or 5 door?

Look on this page here for tyre sizes http://www.wheel-size.com/size/opel/astra/2015/ Tyre size is in the first column. In the third column is PCD, this needs to match between your car and the car they have come off
Tony is correct the Astra j has a pcd of either 115 0r 120, yours ( could well be pcd 115 at a guess,
it will indicate this on the inner rim,)

So I would suggest , and only a guess

That if you do decide on fitting premium tyres 225 40 18 tyres , will most likely suit.


B

Ps Astra mk4 and mk5 have a pcd of 110, astra j wheels simply don't fit, unless adapted at great expence
 

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AON Resident Cynic
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Im not sure on the 18s but Iirc you need to change the tyre size in the ipc to keep the speedo right , i thought there was a configurator for tyre sizes on here somewhere tho


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Or, more simply, use the tyre size as per indicated in the manual.
 

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Generally speaking if you go up a inch take 5 off the tyre wall height

Eg my car has 18s and 40 profile tyres if I went to 19s my tyre profile would be 35
 

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Generally speaking if you go up a inch take 5 off the tyre wall height

Eg my car has 18s and 40 profile tyres if I went to 19s my tyre profile would be 35
Perfecto(Y) well almost lol, the diameter of the wheel between the above two mentioned is negligible, 18 inchers slightly smaller, but makes all the difference in ride comfort, ie more rubber on the road with the 18's


B
 

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Tony is correct the Astra j has a pcd of either 115 0r 120, yours ( could well be pcd 115 at a guess,
it will indicate this on the inner rim,)

So I would suggest , and only a guess

That if you do decide on fitting premium tyres 225 40 18 tyres , will most likely suit.


B

Ps Astra mk4 and mk5 have a pcd of 110, astra j wheels simply don't fit, unless adapted at great expence
Almost right, the J has a PCD of either 105 or 115. 120 is insignia


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All the standard wheel and tyre sizes for the the Astra J are given in our reference thread here:
http://www.astraownersnetwork.co.uk/showthread.php?127522-Astra-J-technical-data-for-reference

To have 18's on a 1.6 you need the wheels with 105PCD (so from a 5-door 1.4, 1.6, 1.4turbo or 1.3CDTI; NOT from a 1.6turbo, 1.7CDTI, 2.0CDTI or any GTC) and tyre size 225/45R18
I second this. Also, this would still give a slightly larger diameter. Usually the default speedo on stock wheels has 5% margin from factory, this would bring it closer to true speed, about 2% off so no problems.
 

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I would still opt for 225 40 18 premium tyres regardless of what's said above ,

Reason is , cost 225 40 18 are popular tyres , tothers aren't so the for mentioned are a cheaper option,

And only get premium tyres of your choice , Budget isn't an option ,

"Its the shoes you are wearing"

B
 

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I would still opt for 225 40 18 premium tyres regardless of what's said above ,

Reason is , cost 225 40 18 are popular tyres , tothers aren't so the for mentioned are a cheaper option,

And only get premium tyres of your choice , Budget isn't an option ,

"Its the shoes you are wearing"

B
225 40 R17 will increase the margin between speedo and true speed from 5% to 7% just to make you aware. Astra J tyre size is not very popular specially for its class. Its tyre sizes are for a bigger class car.
 
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