So I know this might sound stupid, I am not experienced with tires or rims. What if I put rims that go on 19" tires and put them on 21" tires? Would I get more rubber out of the 21"s or would it not work? Or Should I just go ahead and get 19" tires? The reason is because, the little off-road driving I do, and the potholes and curbs around here, it is very hard to keep the rim from getting scraped/scratched. I heard it is also not a good idea to off-road with 21"s. So any input on this would be great.

 

ok, I am going to assume that you are not pulling any legs here...you are trying to get to wheel/tire widths but you are using wheel/tire diameters...a 19" rim is 19 inches in diameter and requires a 19" diameter tire...you will need a 21" rim for a 21" tire....what you want to discuss is differences in tire/rim width, which also gets you into offsets and possible need for spacers...I'll let someone experienced with Cayennes handle that...if you are looking for a higher profile tire so that you have more sidewall you may run into circumference issues...you could talk to Damon at tirerack and see what they have been doing with Cayennes that has worked

 

Thanks for clearing that up a bit. See my friend knows a lot about cars, and I told him I would be getting either 18" or 19" wheels, and he told me I wanted to get just a smaller sized rim. So I got really confused and decided to go ahead and ask on here. Sorry for any confusion, and I am sorry if I sounded really dumb there.

 

no need to apologize...that is why we are all here..to share knowledge...I'll let the Cayenne experts help you with exact info like wheel diameters, width and offsets and then the proper tire size depending on brand...you might elaborate if you want these for street, off road, winter or a mix...what your friend meant by smaller sized rim was probably one with less width...that might work depending on the width of your tires (usually expressed in mm like 245, 275...etc...rim width can vary slightly but there is usually an optimum width for a particular width tire...cramming that tire on a smaller rim can make the sidewall stand up but it will affect the safety and handling of the car and I don't recommend it..(it will also be much more expensive than replacing tires)...you would be better served to get a tire with a higher profile/sidewall (also expressed in mm usually in a range from 25 to 45 for our cars...in other words a 245-35-19 is a 245mm wide tire with a 35mm profile and a 19" diameter...that tire should be on an 8.5" wide rim for optimum performance, although it will easily fit an 8" or 9" rim as well. the problem you can create going up to a higher sidewall (ie 245-40-19) or squeezing the tire on a narrower rim is that you increase the rolling diameter of the tire and this can cause problems with traction control...if you increase profile in the front as well it may or may not work for your application and that is why I recommened you talk to Damon or some of the Cayenne guys here that will know what you are trying to accomplish and how to safely get there

 

I have three complete sets. I stick with what is in the PCM selection and follow Porsche's recommendations figuring that Porsche's engineers really know what they are doing.

I prefer the softer ride of a smaller wheel and have two sets of 18's and the OEM 20's. While my snow tires are the wider size next time I am going with narrower yet slightly taller tires. This should allow me to cut through the chop better, give me an extra 1/4" ground clearance and a slightly softer ride.

Stick with Porsche OEM wheels for reliability and security at speed. Ernie's Alloys is in your neighborhood. Call Ernie. Even though he's in Florida he beat everyone else out and gave me a far better deal. Tell him Dr. Kent sent you. And, no, I get nothing from the referral. Ernie's wife helps him and together they'll get you on the right track.