Fitting 255/40/19 PS4S on V8S?

[dlgis]

I have a V8S with standard 8.5” front and 10” wheels so tyre sizes are 245/40/19 and 285/35/19, and as we all know Michelin don’t sell PS4S in the size for the fronts ( except in US as it fits a model of Cadillac). Has anyone tried 255/40/19 instead?
If you consult tyre calculators the rear 285 is considered the widest suitable tyre for a 10” wheel ( ideal range 265-275), whereas the widest tyre for 8.5” is 255, (the ideal range being 235-245).
Obviously rolling radius/diameter comes into consideration. The fronts are 679mm and rears 682mm in standard sizes. A 255 would up the front to 687mm which i would of thought an acceptable match to the rears.
So back to the question has anybody tried a 255 and any thoughts on compatibility?

[Olas]

does it absolutely have to be PS4S? The size is available in other brands

[Olas]

https://www.blackcircles.com/catalogue/pirelli/p-z...

https://www.blackcircles.com/catalogue/yokohama/ad...

https://www.blackcircles.com/catalogue/michelin/pi...

the 3rd link is a michelin pilot sport 4 in 245/40r19.


re your suggestion of differnet sizes as alternatives, go to www.willtheyfit.com armed with old and new sizes - it gives you a graphical comparison between the two, difference in MM, speedo error where applicable etc etc etc. Once you have this info take a tape measure to your car and you will see if it fits or not.

[dlgis]

I’d like PS4S if possible as the feedback is very good on these especially when compared to the original Bridgestones.

[bogie]

dlgis said:

I’d like PS4S if possible as the feedback is very good on these especially when compared to the original Bridgestones.

To be fair, just about anything is better than the original Bridgestones

Ive been running Yokohama Advan Sport for about 9 months now, very pleased with them, replaced some OE Bridgestones the car came on from the dealer.

[V8V Pete]

dlgis said:

So back to the question has anybody tried a 255 and any thoughts on compatibility?

I currently run my V8VS on V12V wheels with V12V size PS4S tyres on (255/35/19 & 295/30/19) with no problems - no spacers and no clearance issues. The PS4S are as excellent as everyone says they are. I used to use my original rims to run winter tyres but they've worn out and now I've got the Michelins (and an alternative car if it's really wintery) I don't think I need winters any more.

So I plan to put a set of Pilot Sport Cup 2 tyres on my original 8.5x19 & 10x19 rims for track/summer use. Same size issues as PS4S so I effectively have the same problem as you. I think I'm going to go with the same V12V sizes (255/35/19 & 295/30/19) as other sources give a bit more tolerance with permitted sizes on these rims https://www.oponeo.co.uk/advice-and-tips/fit-the-t...

Just tell your insurance company what you've done and you're all fine. They may charge you a few extra £ but at least you're all covered.

[dlgis]

Thanks V8VPete thats really interesting. Certainly the sizes you’ve chosen are a near perfect match on rolling diameter, but they are a little less than the standard 679/682mm at 661/600mm. The lower profiles would no doubt be preferable on a track, for road use I'm still drawn to just upping the fronts to 255/40/19 which gives 687/682mm diameter. Fortunately this isn’t an immediate problem for me as the current Bridgestones still have about half the tread left, so I’m hoping someone else will volunteer as the guinea pig

Good advice on the insurance

Edited by dlgis on Sunday 15th March 13:27

[V8V Pete]

I wouldn't worry too much about the profile. The lower profile PS4S are much more comfortable than the standard V8VS size brick-hard Bridgestones. Either way I'm sure you'll be fine and let us know what you do when the time comes.