strato58

What are the downfalls for using an 11.5" rim with a 305 tire. I think the 997s came with that set up stock....
thanks again
bob

L_perm

My 997.1 TT came stock with 11" wheels and 305s. If you put a 305 on an 11.5" wheel then you'll lose a little rim protection--from curbs and potholes. The wider rim will pull the bead apart by 0.5", but the section width of the tire will increase less than 0.5". Therefore, you end up with less of a bulge, so to speak. Picture it this way, if your sidewall is vertical with the 11" rim (|), then widening the rim without widening the tire will cause the sidewall to lean outward (\). This will have implications for ride and handling also.

I picked up a set of rims for a very good price and the rears were 11.5". Because of this, I ended up with a 245 f/325 r setup. I was mounting PSSs, so I called Michelin about it. They agreed with my assessment, even though the 11.5" is within the range for 305s.

Louis

TT-911

305 on 11.5" is just about perfect.
I have 12x19 with the stock 305 and love the result. It is within spec.
The GT3 RS, the car Porsche developed to be the ultimate track toy, comes stock with a 305 on a 12". Think this says it all.
Furthermore you'll get rid of the awful bloated look in the rear.

Louis, your 325 on 11.5" will look even more bloated, I would not do that. If you can go to 12" at least. Or use the stock tire size on the 11.5".

This is a 12" with 305

L_perm

Already done and not bloated IMO. Just looks like a tire. You say tomato, I say tomato.

What 305 tire are you running that has a 12" rim within its designed operating range?

More bloated...
The 325 is 20 cm wider than the 305. The 11.5" rim is 25.4 cm wider than the stock 11" rim. Therefore, the rim widens by more than the tire. How does that end up causing more "bloat."

The GT3RS may be the ultimate track toy, but how many potholes do you encounter on a track? Isn't the GT3RS more than 500 lbs lighter? Won't it break your teeth on a rough road? I wasn't aware Bob was after the ultimate track setup and all of the non-track issues that come with it.

Louis

L_perm

Denis,
Your rims, by the way, are the concave, one-piece version of mine that are 3-piece, step lip. Seven split spokes. Mine are brushed centers and polished lips.

Louis

jhbrennan

As already stated both the 997 GT3 and GT3RS come with 305's mounted on 12 inch rims. I run the GT3RS wheels and tires on my 2008 TT - 30,000 miles - no problems.

TT-911

No, a 305 on a 12" is not harder, you can't feel any difference.
Every 305 tire can be mounted on any 12" wheel, one issue only, both have to be the same diameter, in this case 19"

This is how a 305/12 and 325/11.5 look, it's clear which one is bloated

TT-911

My previous post, although correct was tongue in cheek, but the above remark needs a serious reply as it is important.

Correct, a 325 is 20 mm (not 'cm' but that is a typo for sure) wider than a 305. But the difference between an 11.5" and 11" is only 12.7 mm (Half inch=12.7mm) . So the tire widens more than the rim by 7.3 mm. Therefore making the 'more bloat' remark.

But in the end it's all good, if you like it that's what counts.

For those of you who like to play :
http://www.rimsntires.com/specs.jsp

strato58

Thanks all..., Denis thanks for the useful info and the cool simulator!

eurotom

Are you referring to the 997.1 RS? If so true but the 997.2 RS runs 325's in the rear

TT-911

You are welcome Bob. Cool simulator, isn't it.

Tom, we are all referring to 997/1 as that is what we are/were discussing here I believe, so far no 997/2 is involved

eurotom

Ok got it, and I say screw it go with 13" in the rear with a 345, go big or go home

TT-911

345 needs 13.5"

L_perm

I understand that you can mount a 305 to a 12" rim, but I've never seen a 305 where the manufacturer's recommended width range went to 12". Maybe no one cares about that, but I listen to how manufacturers recommend I use their products.

As for the GT3RS statements I made, my point was that the answer--it's on the GT3RS, therefore it must be the way to go--is not necessarily applicable. It depends on the person's goal for the car/tires.


You're right. I didn't divide my 24.5 mm by 2. Duh. I guess my car is officially a whale.

Louis

TT-911

What about the manufacturer of all manufacturers , Porsche itself.
Would you argue if Porsche mounts a 305 on a 12" it's not within spec?
Listen, I do not want to go in a back and forth with you and if you think you are right and I am wrong than I accept that. I like you and your attidute in live and a stupid tire debate is not going to change that.
So do what you think is best and all is good.