ADVICE NEEDED re; 245 x 40 and 235 x 40 tyres

Since getting my rear arches rolled and fractionally pulled I reckon I can now easily get 245 x 40 tyres (on the rear only) to replace the 235 x 40 that I am currently running.

My question is this, will the very slight difference in overall diameter between front and rear wheels affect the AWD system in anyway at all, I know that you cannot run staggered fitments on an Impreza because it will wreck the centre diff, however you can run staggered on a Skyline with no problems at all.

If it helps these are the figures.

235 x 40 x 18 has an overall diameter of 25.4" or 645mm
245 x 40 x 18 has an overall diameter of 25.7" or 653mm

This equates to an 8mm overall difference OR only 1.24%

Any help/advice would be much appreciated

You definitely can't run a staggered fitment on an MPS6. My experience had been that anymore than a 4mm difference front to rear will cause binding in the drive train. There's also the possibility of resonant vibration. An 8mm difference would most likely overheat the diff coupling and cause the AWD light to illuminate.

Not sure why you would want to run 245 anyway. Unless you increase the rim width the budging sidewalls of 245's will probably cause your car to handle less well than it does on 235.

^ +1

The AWD of a 6mps more closely resembles that of the WRX compared to the skyline. The skylines have more of a 4WD system than an AWD system.

Quote:

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Originally Posted by kmh001

Not sure why you would want to run 245 anyway. Unless you increase the rim width the budging sidewalls of 245's will probably cause your car to handle less well than it does on 235.

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Thanks for the input but it is running non OE 8.5J x 18 wheels so 245 would not be an issue as far as rim width is concerned.

Quote:

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Originally Posted by 07MPS6

Thanks for the input but it is running non OE 8.5J x 18 wheels so 245 would not be an issue as far as rim width is concerned.

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Fair enough about the rim width, but yeah you need to keep the diameters equal all round.

what offset are you running? cause you will rub with 245 with incorrect offset.

ET48 and there is loads of clearance both inside and outside with my current 235's, 245's would still cause no problems with clearance but it looks like they would with the AWD system.