Wheels And Tyre Sizes

[dalesman]

just had 4 new alloys and tyres fitted. Pirelli scorpion 235/55/r17-99h mud and snow. ( 17'' but lower profile )

Is it ok to use the original 215/70/16 wheel and tyre as a spare??

Original tyre /wheel 16'' ...new tyres/wheels are 17''.

The overall circumference is approx 2'' difference bewteen the two sizes.

Would I be restricted in speed to the extent of a space saver wheel and tyre combination for example??

Vehicle is a Rav 4 GX 1998 5 door ( 43,000 miles from new-one owner-- me! )

Appreciate any feedback. Thanks

[Uncle Bob]

I would think you could use the spare just like a modern car with a "Space saver spare", at a limited speed ,just to get you home :) .

[cfc1]

I don't know if the Rav is constant 4 wheel drive.l. if it is, don't use a different size spare or you could screw up the transfer box.. all 4 wheels need to turn at the same speed... if it can go to 2 wheel drive, then, and only then, will it be safe to use a different size spare.

[AMH]

Pretty certain you cannot do it ...

The rolling diameter is too different - think the manual mention changing tyres in pairs to stop cross-diff issues and I am sure the police will take an interest in the differing sizes - space savers come under different rules as they are specifically marked etc ...

Think you may need to search for the correct spare too ...

[diffman]

Two different sized tyres are not a good idea on the same axle in any diff as the differential gears will continually work(i.e. turn) . As most differential gears apart from the crown wheel and pinion are drip fed with oil the differential gears can run dry on the shaft and friction weld themselves to the shaft. Then when you turn the first corner an almighty explosion takes place !! Also , it's an absolute NO NO to spin your wheels in the snow or mud for any length of time if it's not a limited slip diff as the same thing will happen i.e. the gears will weld themselves onto the shaft. Seen it and had to fix it too many times.Obviously driving a small distance without too much power you could get away with this but not really advisable.

[dalesman]

I have tried to speak with Pirelli but they wouldnt even give me the time of day!! something to do with liability and possible litigation...wouldnt even give me the tyre pressures !! :censor:

I ended up being directed to the technical chaps at HQ TYRES, after waiting on hold for a while though!, who were very helpfull. They gave the same advice as the Local Toyota Dealer ( can't say which one as not the one i take my car for service.....may get upset !! )

The difference in overall size bewtween the 2 wheel / tyres packages is only 2'' in circumference. The only draw back is that the speedo reading shows a margin of error of 2.4% which relates to the speed indicating 60mph when you are actually travelling at 58.5mph ( or something near). This is less than if you fitted 235/16/60 tyres as supplied as an option by Toyota.

Both used the Miata Tyre Conversion website......sorry dont have full link.....but having viewd it myself I found it very helpfull as it shows pics aswell as dimiensions for any combination of tyre.

I asked about the size difference and both stated that due to the minor differences this would not cause major problems unless for example i fitted a corsa wheel on one side and a rav wheel on the other then i could kiss good bye to the diff and transfer box!! And as I was only using it as a spare for short journeys then would be ok. ( on the lines of using a part worn spare with a new tyre on same axle )

Although having paid hundreds of pounds to various breakdown companies over the years, and never had cause to use them, I may just call them out in future to change the wheel!

The only draw back is due to wheel nut head size difference I have to carry 2 wheel wrenches and a set of wheel nuts as there are only 3 on the back door spare.

Thanks to everone for advice and guidance, wish that I found this site years ago!!

cheers!