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 Post subject: Tyre Profile
PostPosted: Sun Feb 16, 2014 9:59 am 
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Joined: Sat Mar 05, 2011 6:45 pm
Posts: 16
Location: Kent
Car Model: ST205
It seems accepted the correct tyre replacement size on standard GT4 wheels is to go from the OEM 215/50 R16 90W to the more available 225/50 R16 92W.

My question though relates to the correct choice of tyre profile: should it be 225/50 or 225/45?

Here's my logic...

On the OEM tyre, the actual profile is (I think) 215 x 50% = 107.5mm
The 225/50 tyre profile would be 112.5mm
the 225/45 tyre profile would be 101.25mm

So which is the preferable way to go? 5mm deeper or 6.25mm shallower?


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 Post subject: Re: Tyre Profile
PostPosted: Sun Feb 16, 2014 10:17 am 
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Joined: Wed Jul 13, 2005 12:14 am
Posts: 3265
Location: Camberley, Surrey
Car Model: ST205
Personal preference in my view.

The higher profile raises the gear ratios slightly and provides slightly more compliance over our bumpy roads.

The shallower profile would do the opposite, not that beneficial in my view hence sticking with 225/50/16.


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 Post subject: Re: Tyre Profile
PostPosted: Mon Feb 17, 2014 1:18 am 
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Joined: Wed Jul 13, 2005 12:06 am
Posts: 4743
Location: Perth, Western Australia
Car Model: ST205
When I used my ST205 as a daily driver I found the 50 profile much more practical and comfortable over the speed bumps and potholes. If its a weekend track toy then this is probably not a consideration :twisted:

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
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 Post subject: Re: Tyre Profile
PostPosted: Mon Feb 17, 2014 6:42 am 
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Joined: Sat Mar 05, 2011 6:45 pm
Posts: 16
Location: Kent
Car Model: ST205
Thank you for the advice, it's an everyday road car, so four 225/50 R16 92W it is then!


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 Post subject: Re: Tyre Profile
PostPosted: Mon Feb 17, 2014 9:51 am 
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Joined: Sat Sep 02, 2006 3:13 pm
Posts: 3679
Location: Bournemouth
Car Model: None
Lower profile gives a firmer feel on the steering but tends too be less progressive when it starts to let go and also tends to find less grip on slimy and rough winter roads.

In my case i went 205-50 and sacrificed mid summer grip for winter predictability.

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