Don’t know if 18” wheels would make a Polo look like a tractor. 17” wheels look fine though (the GTI and BlueGT have 17” wheels as standard).
What are your current wheels? If your car’s a 1.2TDi as your signature suggests, then I’m assuming your current wheel and tyre set up is 6Jx15”, offset of ET38 with 185/60 R15 tyres.
What is the overall spec of the wheels you’re planning on fitting - PCD (bolt pattern) Centre bore size, width (J size) and offset? I’m not familiar with Club Sports; are you meaning the wheels that were fitted to the mk7 Golf GTI Clubsport? If so;
- the lightweight 18” VW OEM Belvedere alloys that were the standard alloys on the mk7 Golf GTI Clubsport won’t physically fit on the Polo as they have a different bolt pattern, so the bolt holes in the wheels won’t line up with the bolt holes in your Polo’s hub.
- the optional factory fit alloys that were available on the GTI Clubsport were Brescia’s and there are replicas of these available for sale, although I’m not sure if replicas are available as an 18” wheel with the correct bolt pattern for the Polo.
- theres an 18” VW OEM version of the Brescia alloys for the current model Polo; they’re the 18” factory fit option on the current model Polo GTI / GTI+ and will have the same bolt pattern as the 6r / 6c Polo. They’re a 7.5Jx18” wheel with an ET51 offset.
- the Golf GTI Clubsport S model (the stripped out version with no rear seats) had VW’s Pretoria alloys. There is an 18” OEM version, and 18” replicas are also available, but I don’t think they’re available with the Polo’s bolt pattern.
The wheels you’re describing as Club Sports may be none of the above though. Whatever they are, I’m assuming they’ll be wider than your existing wheels; probably a 7J or 7.5J wheel. Also, bear in mind some aftermarket wheels have quite an aggressive offset, so if you’re planning on fitting a wider wheel with a more aggressive offset, then that does increase the risk of rubbing when you factor in the wider tyres that you’d need to fit on a 7J or 7.5J wheel compared to your current set up. But it’s difficult to say if there’s a risk of rubbing without knowing all the spec details of the wheels you’re planning on getting.
You need to try and maintain the same overall rolling radius with any new wheel/tyre set up as the rolling radius of your existing set up to avoid any significant speedo reading error. On 18” wheels, that would probably mean fitting 215/35 R18 tyres - assuming the 18” wheels are either 7J or 7.5J. Bear in mind that going from something like a 60 section sidewall tyre on a 15” wheel to a 35 section sidewall tyre on an 18” wheel will make a significant difference to ride quality - the sidewalls on a 35 section tyre will be much stiffer than they are on your current tyres, so the ride would be much firmer as a result. A 215/35 R18 tyre will also be quite a bit more expensive than a 185/60 R15 tyre.
Also bear in mind that fitting different wheels to those fitted to the car when new is considered to be a modification for insurance purposes, so you’d need to notify your insurer to ensure you don’t invalidate your insurance cover. Some insurers may charge an increased premium for fitting non-standard wheels.