Thinking of changing wheels

[Muzzer911]

I know there has been lots of discussion about KN's eating tyres but my front 2 have only managed 4500miles whilst my back 2 have managed over 12,000. With this in mind (and the cost of each 20" tyre). I am considering downsizing to 17 or 18" rims.

The tyres are certainly cheaper but I am wondering if there are any other benefits to having smaller wheels or if in fact this would create more problems i.e calbrations etc.

Any thoughts would be most welcome.

 

[tiskev]

I'm no expert but I think the larger wheels are mostly cosmetic and another way for manufacturers to make added profits.If 18 inch wheels are good enough for standard
they are good enough for me and as others on here have noted the Bridgstones on 18 "
give much better mileage and if you do not have air a better ride ?

 

[gdavison]

Usually the reason a larger rim is used is to decrease the amount of Tyre wall by allowing the use of a lower profile tyre for the same overall "wheel" radius .. Lower profile tyres have less movement on the rim when cornering and also less "flexibility" under compression (bumps) .. Therefore the lower profiles give more predictable cornering and also assist in providing more feedback to the steering .. Downside is the Ride Comfort aspect given any the type (requiring the suspension to provide any comfort). I have also seen some arguments that more alloy wheel / less tyre (depends on Alloy design of course) equals less unsprung weight

With the Cayenne, less tyre movement with the 20's mean the edges work harder in corners hence tyre wear.

 

[Muzzer911]

My front tyres look brand new apart from on the outer edges, confirming your statement.

I do have air suspension so maybe this will help.

 

[Muzzer911]

I think I will bite the bullett this year and stick with my 20's.

Done a bit of internet shopping and found a company (ww.etyres.co.uk - as recommended by Eamonn Holmes!) who are pretty competitive and will come to you. Just got to choose my tyre brand now.

As stated above, Ive got air suspension and find that my car seems to sit pretty low. This is quite noticeable at traffic lights when Rangie's etc pull up at the side. It also appears lower than other KN's. Is this right?

 

[david_yorkshire]

why don't you measure your ride height & compare it against the figures in the manual ?

As for tyres, are you sure you've got the fronts at the right pressure ?

I've done 14K on a set of 20" Pirelli's - the fronts are now at 2.5mm, the rears at 1.6mm depth

Given that the car is predominantly rear wheel drive, I think this wear bias is normal

 

[pwebb]

I bought a spare set like this off ebay and keep the 20" ones for the summer.
http://cgi.ebay.co.uk/4x-Porsche-Cayenne-Alloy-Wheels_W0QQitemZ140383989183QQcmdZViewItemQQptZUK_CarParts_Acc_Wheels_tyres_Rims_Car_Wheels_ET?hash=item20af89adbf

I also swap front and rear to even out the wear on the summer ones. I've found this to be quite economical over the last two seasons and there's enough tread on the winters for another year.

 

[kpd]

Have got a 2005 4.5S (air suspension) on 20 inch techno wheels and I got 20,000 out of my last set of fronts (Contis) and rears are finally nearing a change after 23,000 miles!

The outer edges my front tyres only started wearing badly after geo was done at my last (OPC) service and I'm sure that shortened the life by a couple of thousand miles!