Max Tyre and Rim possible on Liberty GT spec B

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Max Tyre and Rim possible on Liberty GT spec B

Postby RusselWanderer » Wed May 02, 2018 4:43 pm

Hi all. I own a MY07 GT-B and I want to replace the stock 18" alloys with some nicer ones. I am looking at the Enkei Ts9's 18"x8". and i was looking to put a set of 245/45/18 on the rears and 235/45/18 on up front. Was wondering if anyone had experience with these sizes and would know whether or not they would fit. I haven't lowered the vehicle at all so there should be plenty of clearance vertically. but yeah, just want to double check in case.

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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby shav » Wed May 02, 2018 5:05 pm

What is your rim offset? Those tyre sizes are fine as long as your rim offset caters for it, otherwise you will need to rill the guards to clear the tyres.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby jarrenowen » Wed May 02, 2018 6:01 pm

Running different sized tyres front and rear on an awd subaru is a BIG NO NO.
calling @corgiwerx.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby Adrian2627 » Wed May 02, 2018 7:49 pm

Mismatched tyres will lead to premature wear of the centre diff and in some cases the diff catching fire. The symmetrical all wheel drive system relies on the rolling diameter of all 4 tyres to be the same.

Your car being an 07 it came standard with 215/45-18 so going up to a 235/45 or a 245/45 will mean the tyres will be quite a bit taller and therefore have quite an effect on the gearing, speedo accuracy (in this case make it more accurate), acceleration and braking. I can't remember the limits but you may not even get them past roadworthy. On an 18x8 I'd suggest a 235/40-18 which will give you the width but maintain an almost identical rolling dia and keep everything where it should be.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby steveP » Thu May 03, 2018 9:35 am

The myth of the same rolling diameter on all 4 corners doesn't hold water. If you mention it, it's as if you're a baby killer.

Do you honestly think all 4 tyres wear at the same exact same rate? If this had to be the case, diffs would be exploding every day.

I've run staggered on my awd cars. Some set ups included staggered wheels with the same tyre size (different stretch), the same rim size with different tyres and a mix of both. Never had a problem, as well as many other people I know who do the same.

The way you drive and abuse a car will have the biggest impact on breaking parts. We have a word for this in the fitness world; bro-science.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby fedaykin » Thu May 03, 2018 11:01 am

Lol, looks like corgiworks will be in business for a long time.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby BillyCorgi » Thu May 03, 2018 10:15 pm

Get your Short Shift Adaptor viewtopic.php?f=68&t=30525
Get your Gear Shift Rejuvenation Kit viewtopic.php?f=68&t=31240
Get your Centre Differential Rebuild viewtopic.php?f=6&t=31089
Want a custom built Brake Cylinder Stopper? viewtopic.php?f=6&t=31321
Need to hire a Guard Rolling Machine? viewtopic.php?f=6&t=31899
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby Adrian2627 » Sun May 06, 2018 11:02 am

steveP wrote:The myth of the same rolling diameter on all 4 corners doesn't hold water. If you mention it, it's as if you're a baby killer.

Do you honestly think all 4 tyres wear at the same exact same rate? If this had to be the case, diffs would be exploding every day.

I've run staggered on my awd cars. Some set ups included staggered wheels with the same tyre size (different stretch), the same rim size with different tyres and a mix of both. Never had a problem, as well as many other people I know who do the same.

The way you drive and abuse a car will have the biggest impact on breaking parts. We have a word for this in the fitness world; bro-science.


So explain to me how it doesn't hold water? What's your mechanical reasoning behind Subaru's constant AWD system not requiring matched tyres to run correctly and not prematurely wear out the centre diff? We're talking Subaru's system here. Not other makers mostly FF but sometimes AWD systems. Granted, diffs catching fire doesn't happen ever day and it's an extreme example but they will over heat and eventually die due to the centre diff trying to compensate for the different wheel rotating speeds. This is why it is also extremely important to rotate your tyres so they do wear as evenly as possible as the Subaru system requires the tyre's circumference to be within <10mm of each other.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby RX25SE » Sun May 06, 2018 4:43 pm

shav wrote: Those tyre sizes are fine as


No they are not as they have different rolling diameters. Would be fine on a 2WD or one of the many 'part time' 4WD cars.


steveP wrote:The myth of the same rolling diameter on all 4 corners doesn't hold water.


It does with a Subaru.
It's obvious that the only difference in the OPs selected tyres is the tread width, applying this to the same aspect ratio gives varying diameters of 1.33%. While this sounds insignificant, and it is to most cars, it will cause heat build up in Subaru's fitted with manual transmissions as they use a viscous (limited slip) center differential to allow for variations in the average speed of the front and rear axles due to cornering, same as a RWD diff does for the rear axles. The automatic transmissions use a system similar to most other brands where the drive to the rear axle is controlled by a 'wet clutch' which can be applied (or not at all) to increase or decrease the drive to the rear axle. The front axle is always driven. At with any clutch, there is slip involved so this will counter the speed variance between the front and rear axles. Having said that, it's still a bad idea to run different rolling diameters between front and rear.

I have seen a Jeep do some nasty stuff just after new tyres (identical to the rear) were fitted to the front and the difference in tread depth was enough to upset it. Similar situation with a Falcon where it freaked out the ESP.

Take a look at some of the cars that run staggered rims and tyres from factory and you may notice that, due to the different tread widths, the aspect ratio is different to give almost identical rolling diameters.


Don't run different rolling diameters on Subarus kiddies...
Last edited by RX25SE on Sun May 06, 2018 9:04 pm, edited 1 time in total.
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Re: Max Tyre and Rim possible on Liberty GT spec B

Postby blacktop™ » Sun May 06, 2018 8:38 pm

18 x 8 is fine on a gt-b, as long as the wheel offset isn't less than +30. if you're not going to lower the car i wouldn't go lower than +35.

wheel offset doesn't need the be the same front to rear, but rim diameter, width and tyre size does. don't mix tyre sizes, and having said that, don't put a 245/45 on. it will look very ballooned on a 8 inch wheel.
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