danglerb

Depends on how big of brakes you can use, and available tires in the sizes you want. Maybe 17 for the street and 18 for the track.

Chuck Z

It's funny to compare/contrast the wheel/tire opinions here vs. the BMW E65 forums I'm on. There, the bigger the wheel/tire combo seems to be the preference by most. 22s and even some 24" wheels and guys over there really go for that look. My E65 came stock with 21s and that is as large as I would ever want to go..... Here, it appears the smaller tire/wheels seem to be the preferred setup by most. On the BMW forums I feel like the old guy not keeping up with the latest trend......

andy-gts

does the increased diameter cause more rotational mass therefore more difficulty with acceleration and smaller tire patch on ground therefore less effective braking?


andy

123quattro

Aluminum weighs more than rubber. The rolling diameter stays the same as you go up in rim size. You are just replacing rubber sidewall with metal wheel. This increases wheel/tire mass, which is also unsprung weight.
I think the difference is this is more "performance" oriented. 18s or 19s look the best to me on a 928. However, 17s will probably lay down the best lap timing assuming the car doesn't have rotors bigger than 330mm.

checkmate1996

My thoughts exactly!

Chuck Z

Agreed. However, do most here track their cars? And if so, do they use the "street" ties? I suspect not so why is it such an important factor to folks here? If you track the car or autocross and you're serious about it, you're prolly going to have a set of dedicated wheels/tires? No? Stop light racing..... well, that's just not smart unless you don't care about having your car confiscated for "street racing." Not worth the risk to me. I said earlier, there are sooooooo many cars that are faster than our 928s these days your likely to get spanked anyway. What it really comes down to in my opinion is, personal preference. Unless you have a specific need (Drag Racing, DE or Autocross) go with the tire/wheel combo you prefer?

RKD in OKC

The increased 0-60, stopping, and Lateral Gs for larger diameter rims is due to 2 factors. One is weight. Heavier equals slower. The other is contact patch shape. The larger diameter rims are also wider along with the associated tire section width. This makes the contact patch shorter front to rear, and wider side to side. Shorter makes for less acceleration/deceleration grip, wider increases the lateral G grip.

As far as performance goes, even on track, the driver's driving style, capability, and track configuration is going to determine whether the contact patch shape makes much difference.


My personal driving style the highest performance package is 18inch wheels.

IcemanG17

Since "performance" is the goal.....18" all the way....since there are the most tires options...... anything smaller has limited options that will only get worse over time......

When I went from 16" to 18" on my street 928 I was stunned at how much better everything was...including the ride......

Alan

Seems to me that though the rotational mass does go up - some situational braking may still improve net - whenever your limiter is tire grip - since its certainly possible to get a bigger contact patch both length and sectional width on 18"/19" by going wider than stock wheels, and likely you'll have a lot more choices of extreme performance tires too.

Just scrubbing off high speed is still probably worse... emergency conditions probably better...

Alan

danrowland

Just bought 10inch rears and 8 inch fronts from a 2005 911 and want to know best tire size for new Michelin Super Sports or AS3 tires. debating
on 275X35 vs 285X35 or 30 if available for the rear and 225 vs 235/40 for the front. any experiences?

FredR

285 x 30 on the rear.

For the front I am not so sure a 235 is in the acceptable range for an 8 inch wide rim but if it is, this is a better size to run. For sure it wil be fittable. There is also another consideration- offset. If you have wheels with an offset close to the 50mm range, besides having no NSR, you may find it runs very close to or rubs on the fender.

Regards

Fred

checkmate1996

I really like 225/40 on my cup 1 wheels. They are readily available and decently priced for 17s. Going 235 up front may get awfully close to the fender.

eijun

My thoughts:
Use tires/rims to help with car looks (good for shows)
Use tires/rims to help with comfort (cruising & touring)
Use tires/rims to help with getting to and from x & y (snow tires, summer tires, rain tires etc, usually likes long lasting tires)
Use tires/rims to help with $$$$ (cheapest tires and stock rims)
Use tires/rims to help with our speed (0-60 fanatics)
Use tires/rims to help improve our cornering strengths (overtake in the cornering)
Use tires/rims to help with everything race related (wants a little of both for race)
Each year you might get a different set of tires that provides the benefit you are requiring (I say the 3 main categories is pre-GT, GT, GTS, not counting heavy modified cars which includes weight)


Personally I am in the comfort crowd (both noise and road feel). I don't even know what is the best rim size for comfort for my 86.5 (all I know is buy the best comfort touring tires you can afford)

If I were to race, I will take the cornering tires (I don't know the best rim size for it either being I never raced and I never tried different rim sizes for the 86.5).

dprantl

If your 8" front wheel offset is more than 55mm then you can probably use 235/40-18 tires without issue; this size should fit fine on an 8" wheel. 285/30-18 is a very good fit in the rear, but again you need to make sure your rear wheel offset is close to 53mm.

Dan
'91 928GT S/C 475hp/460lb.ft

The Forgotten On

I use Panamera S 10 spoke wheels. 275/35/18's in the rear and 245/35/18 in the front. The tire noise is
a little louder but they corner so much better and are very comfortable to drive on
(101 lane used by semi's and still comfortable sort of comfortable). The fronts only rub the back edge of the fender when you go over a large bump quickly while turning and the rears fit perfectly. Keep in mind this is
an 81 and the extra ground clearance is appreciated with all on the roads after the wind storms recently.
18's are a huge plus especially when it comes to tires, the only good ones for the 16's are the ones used on a lotus Exige.