Question on tire sizes.

Ferrari used 9" wide rims using the XWX 225/70 VR15 tyres for the rear on the 512 BB. The 225 width XWX do look too wide for the 15" x 7.5" width rims imo.

 

check tire fender clearance. it might be an issue.

 

AFAIK, there are likely several specific reasons "Why did Ferrari chose to do this ?", but aside from aesthetics and potential clearance concerns, technically speaking, I can't think of any for not to install 225/70 VR15 XWXs on 7.5" wheels, if you want to.

People change to & use non-OEM recommended tire sizes on OEM size wheels (& vice versa) every day and have been doing it for far over 100 years already.

 

Snips from the Longstone website.

Michelin XWX 215/70 x 15.
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Michelin XWX 225/70 x 15.
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So they recommend between 6" and 8" wide rims for the 225 wide tyres. 9" rims are normally found with much wider tyres than 225 as are on the rear of the 512 BB as OE.

 

I have seen 9" BB wheels in the rear with 265 Avon ZZ's, fit perfectly. and 225 up front on std. wheels.

Alas, not being manuf. at the moment.....

 

Possibly Michelin TB's? Why not, and keep the others on another 'proper set of wheels.

 

Avon CR6ZZ are still in production. we are shipping them all over the world at present because they are sometimes difficult to get hold of, but generally we can get them. they are on here

https://www.longstonetyres.co.uk/vintage-tyres/avon-cr6zz.html

the same seems to be the same where people are srtruggling to get Dunlop Racing tyres, yet we still ship them all over the world

https://www.longstonetyres.co.uk/vintage-tyres/dunlop-racing.html

However neither are actually good road tyres, they are really race tyres; in fact the Dunlop Race tyres are not road legal.

 

These are Michelins current rim recomendations

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this does include fitting a 25/70VR15 Michelin XWX onto a 7.5" rim.

Rim width slightly changes the handling characteristics of a tyre. a thinner rim in theory gives a bit more comfort, and is often what is chosen for the front of a car. On rear wheel drive cars like, old Ferrari, wider rims are often fitted on the back wheels. Ferrari particularly like doing that. 512BB and Some Daytona fitted the 225/70VR15 XWX on a 9" rim when the recomendatiion is max for road use is 8". They did it again with the TestaRossa on fitting a 255/50R16 tyre on a 10" rim when recomended Max is 9"

Ferrari love it. its a racing thing. It gives the tyre a bit more stability.

On a road car you want about an inch of tyre each side sticking out to protect you rim from the curb, but as a racing car you don't care/ Ferrari when it boils down to Ferrari is a bit like a road race car.





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25/70 ??? I think you forgot a 2 - so 225/70

 

Hello Longstone, May I ask if there is any update on the anticipated introduction by Pirelli of the CN72 in size 205/14? Thanks!

 

Blimey

I'm sorry about this. It is proving more difficult to get this tyre through the homologation. Sorry it is taking so long, but this is Pirelli it won't come out untill it is perfect. I will have another nag, but this is being done by their top end technical department and they have recently released some new stuff so i know they have had other fish to fry as it were and i'm afraid reintroducing obsolete tyres comes a bit down the pecking order of priority.