If anyone is running 315/35/20 tires in the rear, I'd like to learn what rims you are using with them. That tire size requires at least a 10.5" wide rim, but you can also use a 20x11 rim. Which companies offer staggered firments in these sizes?

 

Sorry, I had a response prepared for 22" wheels. I do not know anyone running wide wheels on 20". Most are on 22's. For instance, my 305/35/22 are within half an inch as wide as 315/35/20's.

 

Yes, seems like no one offers a 20x10.5 or 20x11 wheels with the correct load rating for a Cayenne. So next decision is between 21" or 22" rims. 22" tires are less expensive than the N spec 21" tires, but their overall diameter is substantially larger than the stock 20" diameter. Always trade-offs involved.

 

Just curious - why would you want to run 315s? Is there a benefit to this width?

 

I personally would have ran 315's if I could fit them all the way around so I can still rotate the front and rear- hence why I went with the 305's.

For me, it is about increased cornering grip in the dry and wet.

 

I'm using OEM 20" Sport Techno wheels staggered, 9" in front and 10" in back with stock size in front and 315's in the rear. Tires are Conti Extreme Contact DWS . It looks good to me. I also added 23mm spacers in the front, to bring the wheels out (they are now almost flush with the fender) and to reduce any understeer tendencies since there is much more rubber in the back.
I can't run very low profiles because of the roads I usually travel on. This is a good compromise for me.

 

I know 315's can be mounted on 10" wide wheels, but every single tire manufacturer states the minimum wheel width for a 315 tire is 10.5" and that's why I haven't done this on the factory rims. Pinching-in the sidewalls loads them in a manner they aren't designed for, and can lead to unexpected and catastrophic sidewall failure. I've seen it happen at some club driving events I've participated in back in the day. Sadly, short of going custom, the only 20x10.5 or 20x11 rims I've found with correct offsets do not have sufficient load ratings for a Cayenne. That's another safety consideration to keep in mind when considering aftermarket rims. At this point, I've abandoned consideration of using 315s - too many issues.

 

I am running Sport Techno 20s, using 295/35/20 PZERO tires, so far its been great, my only big gripe is they stick out a tiny bit further, and as such tend to throw more rocks and crap down the side of the vehicle.

 

Interesting choice. This size has a smaller overall tire diameter than the stock 275/40/20 size by nearly 3/4 of an inch and their load rating is also less than what the factory specified. I'm assuming you've lowered your vehicle to compensate for the shorter tires and are running these on the rear only? At least they are approved for a 10" wide rim.

 

Increased grip is certainly interesting to me. I guess my question would be: does a wider tire actually improve grip? If so, what's the compromise? Steering feel? Anything else?

It certainly seems like it would improve cornering grip, I'd just like to see some data.

 

There is no shortage of physics-based debates on wider tires and enhanced grip. If you want to bore yourself to sleep, here is a cohesive page that says that wider tires increase grip in a straight line and while cornering. However, not for the reasons that you would assume:

http://www.carbibles.com/tyre_bible_pg3.html

 

That's good info, thanks.

I always like to see data when considering a change to the OEM set up. As you know, sometimes changing one thing that could be beneficial has unintended negative effects elsewhere. It makes you wonder why the tires weren't that wide from the factory if they offer better performance.

 

I am running these on all 4 corners. According to Discount Tire's calculator, the overall height is different by a total of .53", so I have .265" smaller sidewall per side. Revs per mile are 704 vs 717, meaning at a speedometer reading of 65mph, I'm actually going 63.8mph. All negligible differences I can live with. As far as the load rating, the factory rating, if I recall correctly, was 2100lbs per tire. The 295's are 2050lbs. Again, factory rating is assuming also that I'm using the vehicle's 7700lbs towing capacity, but I do not have a hitch installed, so no towing. Again, an acceptable compromise on my part, as you said there's always a trade off. All in all, I love the more filled out look, and will probably stick with these for my summer tires.

 

Over half an inch overall diameter is not an insignificant difference when it comes to overall tire diameter. But are you saying you mounted the 295's on your front 9" wide rims? That would be 1.5" less of rim width than what is the minimum tire manufacturer specified rim width for that size tire.

 

I was simply sharing what I'm running on my car and what works for me.