Which Tyresize on which Rim? Answer inside

[Roas]

Link

Datasheets from the ETRTO. I think some of you might find this a useful Information.

So, next Summer some Toyo R888 in 245/40 R 17 on 8 inch rims for me :biggrin:

 

[mark_1873]

you need 235/40 R17 or the standard tyre size of 215/45 R17 for an 8" wheel. Not 245/40 R17

 

[Roas]

you need 235/40 R17 or the standard tyre size of 215/45 R17 for an 8" wheel. Not 245/40 R17

And why would that be? 245/40 R17 is approved for an 8J rim (as you can see further down on that page and the circumference differs only up 0.4% from a 215/45 R17.

It is of course, as you pointed out, not the "standard" tyre size for an 8J rim, true

 

[mark_1873]

235/40 R17 is the closest to the standard cars wheels rolling radius.

 

[mark_1873]

with that tyre size you will also have a larger side wall and more unsprung weight, especially with R888's

the best compromise of a lighter 17*8 wheel would be the 235/40 tyre or 215/45

I have 235/40 just now but when there shot I'll be trying 215/45 for a comparison ( much cheaper aswell )

 

[Roas]

235/40 R17 is the closest to the standard cars wheels rolling radius.

Well I don´t know tyre regulations in Britain. Is fitting a wheel with a slightly larger rolling radius than standard strictly prohibited?

I´ve had 225/30 R20 on my Clio. TUV approved in Germany that is. Those wheels had a rolling radius which is 2.83 percent larger than the OEM tyre.

Even my momentarily fitted 225/45 R17 are larger than those 245/40 R17.

EDIT: Ah okay, weight is indeed a good point since the sidewall is reinforced with metal, got pictures? I´ve had 215/45 R7 Toyo R888 fitted last season. For road use. Loved em. I already have a pair of 225/45 R17 Michelin Pilot Sport Cup and was looking to complete the set, but it´s almost impossible as nobody can deliver...

 

[mark_1873]

If your looking at it from a performance perspective it's the lighter the better imo.

245/40 R17 with the offset of my track wheels would probably scrub the arches under hard cornering and the higher unsprung mass would outweigh the advantage of the wider tyre.

Im not saying 245/40 wont fit, it will but the best compromise for price and performance is 235/40 or 215/45 which are cheaper again