Tyre size and intermittent wiper problem

[Tim Scott]

Hi All, I have a couple of quick questions in the hope someone can help me, please!

I have a 2003 C2 which had 19" aftermarket wheels when I bought it but for reasons I won't bore you with, I've switched them for some genuine period (can I say that about 2003?!) Porsche/BBS 18" 5-spokes (996.362.138.00). I'm now a bit confused about the correct rear tyre size as people seem to be running both 265/35 ZR18 and 285/30 ZR18 on the same wheels. I found a Porsche document online that suggests the former for up to 2001 then the latter for 2002 onwards. Mine is currently fitted with 265/35s but I want to put some decent new tyres on it (Michelin Pilot Sports seem to be the consensus) - and I want to get the right sized ones! Any thoughts?

Secondly, since I bought it, the intermittent wipers haven't worked (they work fine in every other position). I don't have the rain sensor and, after a bit of googling, I've pulled out the dash variable speed dial and also given the relay in the footwell a good dose of contact cleaner but neither of the easy fixes have worked (how often do they?!). I'm guessing one or the other needs to be replaced - can anyone suggest which I should start with?

Thanks in advance!

 

[SteveAndrews]

Hi Tim
Looking in Richard Hamilton's excellent book "The ultimate owners' guide Porsche 911 (996)" the table of wheel sizes and tyres shows that for a 10" rear up to the 2001 model year it would be a 265/35 but from 2002 it changes to 285/30. The fronts changed at that time to 8" instead of a 7.5" front but the tyre size stays at 225/40.

Incidentally, did you find much difference in the handling going from 19" to 18" as I have the larger on my car and have wondered if I would notice any worthwhile change?

 

[Tim Scott]

That’s really helpful, thanks Steve. Looks like the 285s are the way to go in order to return everything to how Porsche intended!

I only drove the car on its 19s a few times before a tyre literally fell apart (they had been stretched...) so I’m probably not best placed to give an informed opinion. I haven’t noticed a huge difference yet to be honest!

 

[wibble]

For information, earlier cars without options had 17". Not many around as many opted for 18". But heard that 17" are more compliant to surfaces on uk roads. Also, believe it was easier to get N rated winter tyres on 17". That may have changed.

 

[Tim Scott]

Given the general state of Liverpool’s roads, I can entirely understand that, thanks Tony!

 

[StillWorking]

I went from 17" to 18" - BBS split rims. The only "cosmetic" upgrade I have made to the car, I just love the look of the splits. I fitted 285 profile Michelins at the rear and will replace with the same. Decent grip and handling and a decent shoulder to protect them (though they do need a refurb!).
Wibble is exactly right. The immediate change I noticed was the ride - I do have MO30 though - less settled and stable. The ride on the 17s is much better but after a visit to CG we have a decent middle ground.