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offset wheels for Forester?


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8 replies to this topic

#1 Forester_Ranger

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Posted 10 September 2003 - 10:53 PM

I currently am running stock 15x6jj wheels with cooper discoverer 205/75r15. I have a 2" suspension lift which has given me an extra 1.5" for tire hieght. I would like to put on cooper discoverer ST 225/75r15 or 235's if possible. The problem is width. If I put these tires on they may rub on the side of the strut tower according to the tire shop. I haven't test fitted them to make sure. I have probably about 1/2" clearence now between the sidewall and strut. the tire shop has suggested putting on negative off-set wheels. But they couldn't find any and said they would have to be custom built wheels. I've been trying to find negative off-set wheels for my car online. I know my wheels are 5 lug 15"x6" but what does jj mean? I think I also have 100mm lug diameter. What is the Off-set of my current wheels and how much of a off-set do I need to make these tires fit. Any suggestions on what wheels will work for this application.

#2 Guest_lothar34_*

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Posted 10 September 2003 - 11:02 PM

I can't remember what the JJ means either.

The stock wheels are 15x6, 5 on 100mm bolt pattern, and I think a 40mm offset.

It looks like most of the available aftermarket wheels have offsets between 35 and 42mm.

IF the stock offset is 40, then a wheel with a 35mm offset may give you just enough room for the wider tires.

I don't know if a 235 will fit on a 6" wheel though. I had 235/75 on my old Blazer's 15"x7" stock wheels, and they just barely fit (the stock tire was 205/75 for the 2wd Blazer, but the 4wd had the 235/75 and I thought they looked much better).

#3 cookie

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Posted 11 September 2003 - 01:00 AM

but wheel spacers are commonly used in raceing. Since a lot of folks race Subies I assume they would be available. They are much cheaper than a custom wheel.
Although I have done many mods like this I don't reccomend the practice unless you have seen someone else spend thier money and the results were favorable.
The reason is that you change the geometry when you change the offset. You are putting a different load on the wheel bearings and axles.
Results I have seen from this were extreme tire edge wear, shot wheel bearings, and broken ujoints.
Stuff like this is commonly done on 4 wheel drive pickups and Jeeps.

#4 Setright

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Posted 11 September 2003 - 01:14 AM

"jj" refers to the shape of the rim's tyre mounting ridge. For obvious reasons tyre and rim must be made to fit eachother :D

The offset of your present rims should be moulded or stamped onto them somewhere along with other info: 15x6JJ ET 55

55mm is my guess, because most Sube rims seem to have this extreme offset. So, a set of rims with 40-45mm offset should give you enough clearance. Remember that you only need to make room for half the width increase on either side!

I strongly second the motion about geometry alterations and bearing load. I would not alter the offset by more than 10mm. In fact, I am running 5mm out on my summer rims.

Good luck!

#5 Guest_lothar34_*

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Posted 11 September 2003 - 01:32 AM

Originally posted by Setright


55mm is my guess, because most Sube rims seem to have this extreme offset. So, a set of rims with 40-45mm offset should give you enough clearance. Remember that you only need to make room for half the width increase on either side!



He probably knows more that I do, so I'd go with that.

Seems kinda odd though that none of the aftermarket wheels had a 55mm offset. Come to think of it, I don't think any were narrower than 6.5" either. Maybe that's why.

#6 Setright

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Posted 11 September 2003 - 05:24 AM

Why, thank you :D

Just for comparison:

My stock alloy rims are 14x5.5J ET55, and I run winter tyres in stock size 185/70R14.

Summer is 195/60R15 on aftermarket 15x6.5J ET50 - take note that standard Sube rims would be 15x6J ET55. Only 6 inches wide.

It is very important that you choose a suitable rim width for the tyre size you plan on using. ABSOLUTE minimum states that the rim should be 70% of the tyre width. My summer solution is 85%, which makes steering response far more direct - and ride slighty harder.

#7 Forester_Ranger

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Posted 12 September 2003 - 06:25 PM

on the backside of the rim it reads "T 15x6j DOT 7 97 J6ER 4" on the wheel near the lugs it reads only "ER".

#8 Setright

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Posted 15 September 2003 - 12:12 AM

Odd. "ER" is that some sort of substitue for ET??

I reckon you will have to try to measure it.

#9 Forester_Ranger

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Posted 15 September 2003 - 10:19 PM

yeah I notice most people have been saying ET. I wonder if the letters ER is code for the Off-set. I also posted this question on another automotive forum and I got an answer of 45mm. so I've got three different answers and not sure which is correct. Most custom wheels that I've found have been 40-45mm offsets. So I might be pretty safe with getting a 35mm wheel. choices are limited though. And the wheels that are 35mm are usually 6.5-7" wide so I pretty much loose my off-set advantage don't I?




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