Here is an excellent site to help you gauge the impact of any changes to your wheel/tire setup: http://www.willtheyfit.com.

 

And other link that is helpful as well: http://www.1010tires.com/Tools/Tire-...0R19/305-30R19

 

Thanks for sharing those sites, StormRune; those are two wheel/tire related sites I haven't come across before.

 

FYI...Carrera GTS and Turbo rears are 11" wide and come stock with 305/30/19. They fit just fine

 

LOBSTAHS AND 305 MICHELINS ALL DAY

 

I use 305 on 11". Looks even better and works perfectly on 2 different sets of wheels (both 11") I've used.

(forgot to mention that mine is a NB, 997 C2S)

 

Similar for me: 997 C2S with 997 turbo 305 wheels and 7 mm spacer. Looks and works perfect. Wheels are aligned with the outside of the body. No contact whatsoever with the body etc from what I have seen. I even think this was specified from factory.

Edit: See detailed pictures of how it looks on my car in this other thread:

https://rennlist.com/forums/997-foru...l#post11878158

 

Odd that Tirerack said that...The Specs on the 305 RE050a says rim width range is 10.5 to 11.5...using the info from the Tirerack website!!

 

Agreed! The 1010Tires.com website shows that 305s are also good for 10.5 to 11.5 inch rims, so 11 seems like it would be ideal (see link http://www.1010tires.com/Tools/Tire-...0R19/305-30R19) .

Just for amusement on a slow 1/1 morning:
With 305s on a car designed for 295s, the car actually rolls 0.91% faster than before due to the increase in circumference, but conversely, you lose 0.91% in acceleration due to the effectively taller gearing. For example, if your car previously ran an exactly 4.0 second 0-60, you would now only get a 4.0364 second 0-60 (which is of course easily overwhelmed by many other factors such as air temperature, surface traction, reaction time, etc.). As another comparison, assuming that you and your car together weigh 3300 pounds, the effective slow down is the same as adding 30 pounds of weight to the car (and again, this is trivial and equivalent to just under 4 gallons of gas in the tank). On the clear plus side of things, you do reduce the vertical gap in the wheel well by 3mm since the sidewall gets 3mm taller!

I'd say that 305s are clearly just fine. I might just go that route next time myself.

 

Go the the Tire Rack site and select the tire brand and you are looking to buy. Select the tire model, then click on the Specs tab. Find the 305 x 19 size, then look at the Meas. Rim Width column. That is the width of wheel that the tire was designed to run on, optimally. Most 305 tires have a Meas. Rim Width of 11" so you will be good to go with a 305 tire.

 

This would be based on new tires only. If the 305's are worn the wall height may be the same as a new 295's.

So what you are saying is that as the 305's get worn = improvement for 0-60

 

11" uses 305, you can look at any tire mfg website and they show tables of their tires and specs, the spec will show the size tire and the size wheel they fit on. if you put a tire on a wheel that is too narrow, it will balloon out the sides , you want it to look flush with the wheel, not ballooned out or sunk in.

 

Your adding 3.4% of tire by adding the 305 to a 11" rim over the 295. Nothing

 

I have 305's on an 11" on my NB. Came from the factory that way with the Turbo wheels.

 

In my post above, I recommended staying with 295's on a NB with 11" rims. Problem is they are sold out everywhere and I destroyed a rear tire on Sat at Thunderhill Hit a chunk of a rotor that exploded in the prior run group. Fortunately, no other damage or on track issues and tires were >80% of life and needed replacement soon anyway. 305's, here I come