Wheel Offsets for 2.8 RSR and Braid BZ Wheels 9 and 11 x 15

[ducatithunder]

Hello All..

So I am going to be ordering my wheels for my RSR build here soon. Im looking at the Braid BZ in 9 and 11 by 15 inch. Look like pretty good wheels for the price and fairly light weight. What are you guys with rsr clones running for offsets? My build is based on a 86 Carrera and suspension with steel RSR flares from Mark Darby over at RS 911 in the UK. Will have a 3.6L 993 power plant and eventually 930 turbo brakes. Will be running a set of custom cut Avons slicks from Kraus racing with a 25inch rear dia tire and 24.5 inch front. Ive asked a few guys and got 9et14 thru 9et17 for the front and 11et-8 for the rear. Others have said 9et-3 and 11et-27 and these seem to be Braids standard offset for the 911 RSR sizes. Really dont want to have to run a spacer more then what’s already on the hubs now. Thanks Guys!

[jameshtaylor]

Just ordered some Braids for my 74 with their RSR 49mm offset. But I don't have flares and am running much smaller wheels and tires, not relevant to your situation. If you have a tire and a wheel in your car now with the flares in place, you can use this website to compute the offset you need. http://www.rimsntires.com/specs.jsp This works well, but it can only tell you how to change from a baseline case.

[ducatithunder]

Thanks ... Yep they look like a great wheel. Im curious what others are running with rsr flares and 15 inch wheels. I have my flares but dont want to weld them on incase I have to cheat a little to get the tires and wheels to fit. Fitment looks great so far. I dont want to order the wrong offset and get stuck with the wheels or have to buy and return until Im happy. Braid has been somewhat helpful but they seem to think that something other then the standard offsets of -3 and -27 would work better.

[uptheorg]

If you are building a replica, you don't really need to stick to 15" wheels -- especially with backdated bodywork. My car was backdated to 1973 RSR from a 1984 Turbo-look carrera, so the original factory fenders didn't need modification. I just got my Lindsey Racing P2's (9x11x17) last week, so I don't have any photos yet, but I will say they don't look too large, although purists will disagree. I believe the 15" wheels will be difficult to find rubber for. As far as offsets and spacers, the car comes with 28mm spacers on the rear which I removed and had Lindsey build a deeper rim. I am running the rears with no spacers and they fit perfectly. I don't know the offset, but if you work with Mike Lindsey, he is very knowledgeable and will give you the right setup.

[C.Plavan]

Braid will soon be making 17's. Which not period correct, I would like some other race rubber to use on my car other than Hoosiers. Plus, Fuchs are getting old. I found a crack on one of my 15x8's this year.

[YTNUKLR]

This may help you calculate what offsets will work for you:

http://www.1010tires.com/wheeloffsetcalculator.asp

With an RSR/930 body car, no spacers, and standard 911 hubs/suspension, the factory 73RSR offsets are very close to what you would want: 9"et+3, 11"et(-)27. The Braid 15" RSR changed it slightly on the front: 9"et(-)3, 11"et(-)27.

Here's a rough standard that should be pretty safe :
-for the tightest inner clearance in front on a 9", you could run a 9"et+18 with no spacer. For the tightest outer clearance in front on a 9", 9"et(-)5.
-for the tightest inner clearance rear on 11", you could run a 11"et+10 with no spacer. For the tightest outer clearance in rear on 11", 11"et(-)32.

With long studs and spacers you can run anything more positive offset

This should get you going with the calculator to play around and see how it works,

[ducatithunder]

Thanks guys. I've been back and forth a while back with 17s vs 15s. Got all my core wheels to send off to mike or Jim to make me a set. I'm def going to go the 15 inch route. Just looks right. The braids are the right price and are new. Not much more then the 17s cost. I have 17s on my 65 cobra and they look ok but when I park next to one with 15 inch knock offs there a noticeable difference. Kinda ruins the look. Won't make that mistake this time around.

Scott .... Thanks for the info. That really helps out alot. I wonder why if the standard rsr offset works why don't more use it??? Is it because of the larger 17 inch wheels and fender fitment. All the guys who gave me the offsets of -8 and 14-18 all ran 17s on 315-335.

So much more homework to do. Thanks!!

[YTNUKLR]

those more positive offsets give you a little more room to 'play' with spacers and such. The Braid sizes are not 'maxed' but you have a little less leeway with the offsets. In my opinion, for whatever it's worth, the car looks best with the deepest wheels that one can fit, essentially (most negative offset).

Are you sure the recommendation for a 11et-8 was correct? I ask only because a 315-335 is a pretty big tire for an 11" wheel. That's pretty much the max size you can fit under the fender, and it might even take some work with a 335. I could find this a lot more plausible if this was a recommendation for a 12"et-8 on a 315-335.

You'll find that the experts here like the michelin TB5 tires , 18/60-15 & 23/62-15 (search Longstone Tyres). They look 'right'. Those are goddamn expensive tires so an alternative that is correct height wise and vintage-looking is the Hoosier Vintage TD S. I don't know about the michelin TB5, but this TD is a bias ply tire. Hoosier make a 8.5x25.5, and 10.0x25.5 tire which is great, but they aren't technically DOT legal. Goodyear makes a blue streak tire that can work, not DOT legal, and really tall (for Cobras). Same story for Avon cr6zz tires, which are DOT-too tall in my opinion. The Hoosier R6 245/50, 275/50 combo seems pretty excellent actually, DOT and the right height, BUT Hoosier recommends no more than 9.5" rim width on the 275, and supposedly bad consequences if this is not followed!! They make a 275/35 which they do recommend on an 11" wheel, but it has an extremely SHORT 23" diameter! There are not a lot of options.

I'm going down this road, and I've decided to go for the hoosier Vintage TD S 8.5/10.0X25.5 tires. They aren't DOT, but whatever...we'll see how it goes. If I win the lottery or a rich uncle dies, I would order the Michelin TB5s. If my TD's blow out (they're light construction for street use), they're half the price of the Michelin so you're still ahead. I may try the Hoosier R6's 245/50 & 275/50 with some grooves cut in them for street, and we'll have to see if the 275/50 on an 11" rim is really a problem, as Hoosier says.

If the TDs blow out a bunch, or puncture, which may also happen with lightweight grooved slicks, I'm going to make some custom 16" deep offset vintage race wheels in 8/9" so I can run normal high performance street tires, 225/50/16 & 245/45/16. I'll make the offsets so they still look like RSR wheels...semi period correct even if I can't run the 9/11 RSR wheels all the time. Yes 17s open up some options but I do not think they look right. The only thing that could even come close to looking cool and having some usable street tires, is a deep vintage 8/9x 16" combination.

One other thing...generally it is preferable to have a more 'positive' offset in front for scrub radius. Do a little homework on scrub radius. The 9" RSR fuchs are not great in this regard. It's kind of like a go-cart setup: the deep dish wheels and large positive scrub radius means it's going to bump-steer rather significantly, and need a fair amount of caster to keep the car stable. But, again, it's nigh impossible to have a good scrub radius and also have a correct looking 73RSR.

That said....a 73RSR on 9/11 Fuchs is worth the pain and issues. IMHO

[ducatithunder]

Scott ... Yep I got those offsets from Bill V. and Jeremy over on pelican. A few others had comment on the same -8 for the rear and 14-17 for the front. Jeremy mentioned he might be able to run 335 in the rear but it would be tight ... He also ran slight spacer in the front. I saw the same thing on the mich TB's. They were stupid money. Roger set me up with avons as they have had alot of luck with them on 911 rsr builds. I asked about the billboards as I was familiar with them on cobras but they were to tall and might rub. I was going to run a set of avons that Roger Kraus racing was going to groove for about $450 a tire for the front and $470 for the rear. My only concern is having enough wiggle room to still have the wheels fit on a variety of tires if need be. The avons where 11 inch tread area and 13.5 cross section overall if I remember correctly ... does that seem correct? I'll have to dig up the email with the specs. Tire height was 25 inch rear and 24.5 inch for the front tire height. Seem to be the perfect height. I agree that the deeper the better. Looks like the standard braid rsr offsets will work out well then.

[Kaefer]

Be careful of tire diameters! It's easy to run 23" or 24" tall tires on RSR offset wheels. It's not so easy to run 25" or 25.5" tall tires with RSR offsets.

Here's my suggested offsets for widebody 911s, regardless of wheel/tire diameter:

9" +12

10" -26

11" -13

Just my $0.02. YMMV.

Edit: One more thing - if you are building a true RSR clone then the answer is simple. 9x15 +3 up front and 11x15 -27 in the rear with Michelin TB tires all around!