Goldmember

As you can see in the thread below, I have the 21" Wheels with Dunlops Summer Performance Tires. While I very much like the look and the ride of the 21s in town, I am thinking of purchasing a set of wheels and tires to use for long distance trips.

I have a couple reasons for wanting to do this. First the replacement cost of the Dunlops would be around 1600 with mounting, road force balancing and tax. Having a set of tires for long distance trips would save wear and tear on the Dunlops.
Second the improved ride from say a set of 18" with Continental Touring tires on them. These tires would be cheaper to replace and maintain.
Third would be improved gas mileage from a smaller tire. I haven't done any research on this but I am guessing there would be an increase in efficiency from having the smaller tires with less rolling resistance. I currently manage 19mpg on the interstate with cruise set at 70mph. I can't imagine that the economy would go up more than 2mpg but at $3.30 per gallon on an 800 mile trip that would result in only about $15 of savings.

So my question, in your opinion is it worth $600 for a set of 18" wheels and tires for use in long distance travel in the Q? Would the ride quality be noticeable? Would the fuel efficiency increase?

mksap11

18s will have more sidewall so they should have higher ride comfort. You give up handling to get this, however, and I'm not sure how the fuel efficiency would increase. The big problem with your numbers is that your $600 figure only accounts for the tires. You'd also need rims and TPMS sensors (unless you want to live with the fault on the MFI screen all the time). Aftermarket sensors from Tire rack will run you about $300/set and a decent quality set of aftermarket rims about $1200/set.

I personally wouldn't do it, at least not for the reasons you mentioned. I do have a dedicated set of 18s that I use for winter driving, however

Goldmember

<a href="http://cgi.ebay.com/ebaymotors/18-Porsche-Cayenne-Wheels-Tires-OEM-VW-Touareg-Audi-Q7_W0QQcmdZViewItemQQcategoryZ66484QQihZ007QQitemZ 170119297257QQrdZ1">ebay linky</a>

Not sure if the TPMS Sensors in these would work or not though.

mksap11

Otherwise you're looking at about $420 on top of the cost of the wheels (~$300 for sensors, $120 to unmount your tires, install the sensors and re-mount/balance

Double_Dip_A6

I would check to see if you dealer has a "tires for life program which replaces the tires for as long as you have the vehicle. It cost about $3000 or so and requires you to rotate and balance every 5000 miles. However almost anything you can imagine going wrong with a tire is covered. Normal replacement on the 21" is 10K-12K miles. Also covers wheels as well.

Outside of that I would still stay with the 21". You would now have 2 sets of tires to worry about and maintain. Since they never wear at the same rate you could find yourself buying more often that you expect. Save your $$ for when you need the 21s