BIGGER TYRES

[Larry225]

I'd like a slightly bigger tyre on my car other than the 225/40/18 Dunlops...roads down my way aren't that great. Would 235/40/18 or 225/45/18 Dunlops be better and if so which one? I think the 235/40/18 Dunlops, but I don't know if someone has good knowledge to impart.. Thanks.

[Larry225]

Larger diameter would technically give very slight inaccuracies in both speedometer and mpg readings but I think mpg would be improved (marginally) and accelaration would be improved (marginally) (I think lol). However increasing the width the rolling mass of the tyres would increase the rolling resistance slightly so the engine would need to produce more energy to spin the wheels. I think you'd need some crazy software to work out if one would cancel the other out or one would overide the other. Whether increasing the the sidewall by 11mm would be very noticable comfort wise I could'nt say, may just be better to try and find a tyre that gives a better ride comfort than the Dunlops. Loads of tyre reviews on the web. Alternatively sit on a cushion!

ps for information the sidewall figure is a % of the width ie 40% of 225mm = 90mm

Actually, I'm looking to find a better tyre for this car. Thanks for info, but the cushions must stay at home!

Regards.