Tyres, but not the usual question

[Paddy_R]

I've managed to get a set of genuine Cup Racer Speedlines and I've had them refubished by a local company (Nu Luk Wheels, expensive but the best in the country not that I've a great choice). The wheels now really do look like new. I will be fitting a set of Bridgestone Potenza RE050As but my question is what width? As most know the cup racer Speedlines are 8 inches wide so are wider than the normal alloys. I've been toying with the idea of fitting 225 as opposed to the normal 215 but I just can't make my mind up. I'll be keeping the side profile at 45 though. Has anybody any experience of this? Or any pictures?

I hope you all can understand my query.

 

[CL10]

Just got 215 on mine and there isn't much stretch (not noticeable), can't see much point in changing the tyre size unless there is a huge difference in price.

 

[GrumpyTwig]

225s are the more natural width for an 8J rim, 215 will be fine but depending on he tyre may look more or less stretched. The thing to remember is 225/45 will up gear the car slightly by about 3mph iirc but hardly noticable I found 225s generally cheaper too.

 

[Paddy_R]

From what I can find the 215 are cheaper, by around £17 per tyre so a noticeable amount.

 

[mini_dh]

i put 215 40's on my cup racer wheels

 

[200 Gordini]

Tbh I'd stick with the 215's pal

 

[CL10]

225s are the more natural width for an 8J rim, 215 will be fine but depending on he tyre may look more or less stretched. The thing to remember is 225/45 will up gear the car slightly by about 3mph iirc but hardly noticable I found 225s generally cheaper too.

Would there really be a difference in the speed reading? 225/215 is obviously the width so can't logically see how it'd change the gearing?

 

[GrumpyTwig]

Would there really be a difference in the speed reading? 225/215 is obviously the width so can't logically see how it'd change the gearing?

225/45 vs 215/45 yes there would be a difference. It doesn't change the gearing but effectively gears up the car slightly due to the circumference/rolling radius being larger.

Don't forget the 45 in 215/45 is the percentage of side wall height to width so well..... I'm sure you get the idea.

 

[Iain 007]

i'd go 225/40 if you can get them

 

[CL10]

OP: Can upload pictures tomorrow of the rim on a 215 tyre if that helps.

 

[Foxspeed]

Would there really be a difference in the speed reading? 225/215 is obviously the width so can't logically see how it'd change the gearing?

the profile changes as its a % of the tyre width...

215/45r17 = radius 196.44cm dai 62.53cm side wall 9.68cm

225/45r17 = radius 199.27cm dia 63.43cm side wall 10.13cm

so would gear up by 1.4%

30mph = 30.4mph 60mph = 60.9mph

 

[CL10]

↑

Interesting, thanks

 

[Paddy_R]

the profile changes as its a % of the tyre width...

215/45r17 = radius 196.44cm dai 62.53cm side wall 9.68cm

225/45r17 = radius 199.27cm dia 63.43cm side wall 10.13cm

so would gear up by 1.4%

30mph = 30.4mph 60mph = 60.9mph

So even at 60mph its still less than 1mph difference. I'd say there's probably more of a difference between a brand new tyre and one at the legal minimum.

OP: Can upload pictures tomorrow of the rim on a 215 tyre if that helps.

That would be great. I don't have any. I bought the rims without tyres and these are the first ones I will have fitted.

 

[Foxspeed]

8inch rims can take tyres from -

min 215 / 225 / 235 / 245 max

 

[CL10]

That would be great.

Hope these help mate - 8j rim on a 215 width tyre.





That's also the cleanest my wheels will ever be lol!

 

[Foxspeed]

225 then from that picture for me (if i was doing it) - dont like the euro-vw look ;/

 

[Foxspeed]

So even at 60mph its still less than 1mph difference. I'd say there's probably more of a difference between a brand new tyre and one at the legal minimum.

yeh its not alot well within the 2% limit i think that is recommended :thumbup1:

 

[Fernandez]

225's are what most manufactures fit on an 8J rim. Interestingly a lot of OEM 7.5J rims come shod in 225's

 

[CL10]

225 then from that picture for me (if i was doing it) - dont like the euro-vw look ;/

Obviously the camera angle accentuates the rim width, but they're definitely not up to the extreme tyre stretch you see on euro-look cars haha!

 

[Paddy_R]

225 then from that picture for me (if i was doing it) - dont like the euro-vw look ;/

Was thinking the exact same. I have a particular dislike of stretched tyres.

Thanks CL10. The photos are a big help.