Sport owners - Tyres

[PDaddy]

Hi Guys,

Which tyres are you most happy with on your sport. I'm looking at :

Vredestein ULTRAC 225/40 ZR18 92Y XL Rim-protection

Thing is there are 215/40 R18s on the car at the moment, would the above fit?

 

[aceman]

they will probably fir but your speedo will be out due to the wider cross section. General rule of thumb is that you reduce a profile size for an increase in cross sectio hence you would need 225/35 to keep the same rolling radius. I would stick with the same size if I were you as your mpg is likely to fall as well.

 

[PDaddy]

The 215 is a very rare tyre size though and thus very expensive! car has 4 different tyres on at moment, each at various stages so might not have a choice but to go 225. will the ride be affected much by the 225/ 35 / 18. mainly motorway driving.

 

[Rallye Dale]

Width has nothing todo with rolling circumferance so speedo will read correct,profile will alter reading

http://www.etyres.co.uk/car-tyres-u...eReinforced=F&tyre6Ply=F&tyre8Ply=F&tyre4X4=F

http://www.etyres.co.uk/car-tyres-u...eReinforced=F&tyre6Ply=F&tyre8Ply=F&tyre4X4=F

 

[PhilOfCas]

Width has nothing todo with rolling circumferance so speedo will read correct,profile will alter reading

http://www.etyres.co.uk/car-tyres-u...eReinforced=F&tyre6Ply=F&tyre8Ply=F&tyre4X4=F

http://www.etyres.co.uk/car-tyres-u...eReinforced=F&tyre6Ply=F&tyre8Ply=F&tyre4X4=F

morning RallyD, r u sure on the circumference info ?, in't the profile (and therefore circumference) a ratio/% of the width ?, the greater the width, the greater the height for the same profile rating ?

 

[PhilOfCas]

morning RallyD, r u sure on the circumference info ?, in't the profile (and therefore circumference) a ratio/% of the width ?, the greater the width, the greater the height for the same profile rating ?

http://www.blackcircles.com/general/sidewall

This confirms my thoughts

 

[CupraR-Rog]

Phil, you are correct that the aspect ratio is as a %age of the tyre width

And to the original question - I say go for it!! Every VAG car I've driven has had very poor speedo accuracy - overreading by much more than other cars I have driven, and so your speedo will probably be more accurate with the larger tyre!! Check with a satnav or other gps device before you make the leap to see how far out your speedo is!

 

[Rallye Dale]

,always thought that if you went up a rim size you just drop a profile

 

[CupraR-Rog]

In some ways, you're correct - a 195/45R16 will have a near identical rolling diameter to a 195/50R15 for instance, which is similar to a 205/45R15...

Think all the info you'll ever need is here - http://www.carbibles.com/tyre_bible.html

 

[PDaddy]

Cheers folks, ended up getting the ultracs, very happy with them, very low noise and so far plenty of grip.