To all you wheel guru's out there a question. Will 11 inch rims fit on the back of my NB 993. I know offsets are a big factor but I don't have those. If it helps the rims are techart formulas 18x11's. They came off of a NB 996. Thanks for your help.

 

They should fit, depending on ET and alignment of course.

Comparing 10" wheels with 65 offset (OEM size) to a 11" wheel with 56 Offset will bring 11" rim out 39.4 mm more and inside 11.4 mm more.
With 65 offset outside will be 30.4 mm more and inside 20.4 mm more.

You can measure your car and see if it tentatively fits but you NEED to know the offset before you can check anything or say whether they'll fit or not.

 

Finn- Thanks for the info. Any idea on how I can find out the offset? On my 5 spokes it is stamped by the valve stem but the techarts have no marking what so ever.

 

I believe David in LA is running 11" in the rear on a NB.

 

Geroge A who is on the board is running Forgeline's with 305's on his NB coupe. Maybe he will post a picture or two. Probably not necessary for a street car to run 11 inch widths.

 

Are you sure they are 11 inch? www.techart.de shows only 10.5 and lists all the offsets for the Formulas.

Best of luck, they are awesome rims.

 

Greg- Your probably right that it isn't necessary to run 11 inch rims but I love the look of the formula and the one's I just got are 11 inch. So....

Randy- I measured the wheel and they are 11 inch from lip to lip. Is this the correct way to measure them? Also thanks for the link to the ofsets I'm just not sure which one mine are.

 

The correct way to measure wheels can be seen here


rim width is measured bead to bead, not face to face

 

Dan,

This picture shows well how to measure different rim measures.

 

Bill,

You beat me!

 

If you have them and they have tires mounted, just put them on and see if they fit. Ease the jack down and be careful if they get close to the fender.

We will have to have another Julian run and you can show them off!

 

Yeah but your pic has more stuff in it :

 

Bill, Finn- GREAT INFO GUYS!!! Thanks. My guess is that the rims are 10.5 sense they measure 11 from lip to lip. I feel better now.

Randy- I'm getting tires for them on thrusday so I'll find out then if it all works. After the pics above I'm feeling much more confident. What scares me is I've never seen a 993 with these wheels. In my minds eye they are going to look amazing. Question is why hasn't some one else done it before??? As for a run to Julian that sounds great, just let me know when!

 

There is some variation, but most wheels that I have measured(and thats a lot of diffent wheels) measure ~11" face to face for 10" bead to bead.

in other words there is usually ~ .5" per side for the flnge thicnkness.

I have never seen < ~.65" per flange

 

Trying to put 11" wheels on the rear of a NB 993 can be done, but why do you need to do it? If they do not fit well, but can be made to fit, like adjusting camber, rolling fender lips, etc....it may not be worth the effort. Most folks I know that want large wheel sizes want them because they want more rubber for racing. In order to handle an 11" wheel with associated rubber, you usually need to change your chamber, have the eact offset of the wheel, and possibly roll your fenders to have the clearance. Again, is this what you really need?

I have 10.5" wheels with a very aggressive offset for a wider track and require a fair amount of camber, rolled fenders, and a good alignment.