TCCoA Forums banner

1 - 12 of 12 Posts

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #1
Im looking around for some new rims for my TBird and need a bit of advice.

They are for a 94 LX with the 3.8L v6.

I have a set of 17" - 7" American racing 686's
http://americanracing.com/appguide/final.asp?section=app&carID=378&picture=686&desc=15"&detail=6867714&year=1994&make=FORD&model=THUNDERBIRD,LX

I am looking for a set of rims to put highway tires on for long road trips, the Toyo Proxes4 are great for the city but suck on the highways. I want to get some black rims or dark grey for a little different look since I already have chrome rims.

The AR 686's have 42mm offset and 144mm (5.675") backspacing which fit pretty well with a 1.5" Eibach spring drop. With 245/45 ZR17's the front tires just barely rub the wheelwell when the wheel is turned all the way.

Closest thing I have been able to find that I like is a set of Enkei PKR's - 7X7.5-115/108 38BM. Do these numbers mean it has a 38mm offset with 115 backspacing? Im not too good with wheel specs and salesman will tell you anything fits. Will these wheels be tucked in a bit further? Im not sure how to judge the backspacing.

I was hoping to put 245/50's on them. Im just concerned that the wheel will be in too far.

If anyone has any suggestions on places to check online for wheels fire away, Ive only checked Tirerack and Discount Tires so far. I really like the Enkei PKR's but am not sure if I should try them.
 

·
Registered
Joined
·
3,726 Posts
I think you will find that the 115/108 reference means they fit both 5 on 4.5 and 5 on 4.25 bolt pattern.

As far as backspacing, I don't know. they are .5 inches wider, with less offset so they will be farther out towards the fender lip.

They would be 5.74 backspace, 2.26 front spacing, were your current 7 inch wide ones are 1.825 frontspacing. Can you go with the wheel almost half an inch further out?

My 9 inch wide wheels have 6.295 backspacing, 3.205 front spacing, I have 245/45/17 tires and a supposed 1.6 inch drop, and I could drop it from the sky with the wheels turned and not have tire to fender contact.
 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #3
Yes I think I could go out 1/2 inch, theyre tucked in pretty good right now. This next weekend Im going to spend all day saturday cleaning the interior and starting on replacing some of the interior pieces so I'll post some pics to see what you think.

I was also thinking of changing the tire size for the new rims to 255/50 17's so I'll have to check tire width too. I think if I put the 255/50's it might rub a bit more on the wheel well so bringing it out a little would help but I dont want it out too far.
 

·
Registered
Joined
·
575 Posts
5-115 = 5-115, 5-114.3=5-4.5 Most after market dual drill wheels will either be 5-100/114.3 or 5-108/115. Please do not confuse 5-115 and 5-114.3, .7mm will make a big difference.
 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #5
Ok heres a pic of my back tire, and you can kinda see the front, I dont think 1/2 inch will affect it much.

 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #6 (Edited)
Well after reading a bit about wheel offset Im not so sure its a good idea to have less offset. The rims I was looking at really doesnt say what the offset is or is that the 35? .

maybe Im confused but this is the way I see it- New rims are .5 inches wider, so that adds .25 to each side of the center line. The new offset is 35mm as compared to the old 42mm so even though Ive added .25" to the positive offset with rim width, the offset is 7mm less which would bring the wheel back in a bit. So even though I added .25 rim width to the street side the offset change will bring it back in 7mm or 0.27559". But half of the 0.27559" goes to the backside as well

So on the street side of the wheel: +0.25" for rim -0.1257" for offset Which would be -0.13. So considering the wheel width and the offset it should only stick out about 0.13"

So for the backside: +0.25 +(half the offset)0.13= 0.38" deeper into the wheel well. is that right?

If thats not right I'll have to give up new math ;)

If I can get this figured out I may just get 18" 's but I dont want to mess up my handling either. My current tires are 9.8" wide but am looking at some 235/50 or 245/50 18's but they are a whole 2 inches taller and dont know if they would fit the front.
 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #7
maybe Im confused but this is the way I see it- New rims are .5 inches wider, so that adds .25 to each side of the center line. The new offset is 35mm as compared to the old 42mm so even though Ive added .25" to the positive offset with rim width, the offset is 7mm less which would bring the wheel back in a bit. So even though I added .25 rim width to the street side the offset change will bring it back in 7mm or 0.27559". But half of the 0.27559" goes to the backside as well

So on the street side of the wheel: +0.25" for rim -0.1257" for offset Which would be -0.13. So considering the wheel width and the offset it should only stick out about 0.13"
Bump
 

·
Registered
Joined
·
3,726 Posts
I am pretty sure you need to add .25 to each side (.5 total) for the lip when figuring the backspacing. I know the lip edge to tire bead seat is substantial on my rims.

Current:

17x7 42 mm offset

7.5 inches/2=3.75 inches + 42mm (1.65 inches) = 5.4 backspacing (2.1 front spacing)

17x7.5 38 mm offset

8 inches/w=4 inches + 38mm (1.49 inches) = 5.49 backspacing (2.51 front spacing)

I think you have a ton of space between the lip and the knuckle on the inside, and I don't know if you can do .5 of additional front spacing moving the wheel towards the wheel well lip. I have over 3 inches of front spacing and I have plenty of room, BUT I would prefer to have less front spacing, but I can't with 9 inch wide wheels.





and the knuckle side with 6.295 backspacing (.75 more that what I am sure the 7.5 38mm offset ones should have):
 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #9
Thanks for helping me with the math on that, its kind of confusing to me. But that makes alot of sense now that I can see it spelled out. I have about an inch between the inside of my front tire and the top control arm so Im not sure if I should go a whole lot wider right now. My current tires are 9.8" wide and I can go out 0.5" on the street side with it not sticking out as far as yours does.

I double checked the wheels I was looking at and discovered they arent 7.5"s but 7"s.

17X7 5-115/108 38BM.

they are Enkei 17x7, with 5-115 and 38mm offset. The BM is Black Metallic. I have always wanted a set of black rims for it and now Im getting them, these are a dull flat black/greyish look. Hot wheels (Red Line) makes some but are glossy and just saw they posted some Momo's today on Discount Tires site for MN12's that are Anthracite-

http://www.discounttire.com/dtcs/findWheelDetail.do?rcz=85225&mk=FORD&rc=AZEINT&yr=1994&wd=17&dVeh=dVeh&pc=45752&rw=&vid=001797&bp=

I may look into those but they are almost $200 a piece. I really like the Cobras and Cobra replicas but everyone has them. Although maybe some day I will get some 9" Cobras. Anyways if I get the Enkei's they will fit good, may even get 18" 's.
 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #10
I think for now Im going to stick with 17" wheels and experiment with tire sizes. I like the 50's more than 45's and 40 is definitely too low for my taste. I have 2 sets of wheels though, one with street tires one with highway tires. I will keep the highway ones 17's for sure so I can have more sidewall but may go to 18's or 19's for the street ones. I will end up with 4 sets of wheels eventually :)
 

·
Registered
Joined
·
3,726 Posts
A 7 inch wide wheel with a 38mm offset is within 1 mm of the stock 16x7 wheels (my 16x7 7 spokers on my 89 Cougar off my 97 Sport are anyways), they are 16x7 39 mm offset.

I would love to have 8 inch wide in the front, 9 or 10 in the rear or a different offset for the 8 in the rear. I will probably get some spacers for the rear to move the 9 inchers out because they are way inside the wheel wells.

Good luck with whatever you choose. I know the cobra rs and bullitts are overdone, but they look good! I am starting to see a bunch of MN12s on 20 inch spoke wheels locally, and they look good. Only thing I hate are the reverse high negative offset wheels that are entirely out of the fender, which is also common where I live.
 

·
Premium Member
Joined
·
1,150 Posts
Discussion Starter #12
That would look great to have different width wheels for front and back only downfall is you cant rotate them. I like the way my 245's are tucked under the wheel wells right now and have thought of getting even wider tires for the back but 17" tires are hard to find with 50-55 sidewall wider than 245. They are out there but the selection is pretty slim. For the Toyos I have they dont even make a 245/50 17, 245/45 17 is the most sidewall.

Ive seen a few Thunderbirds with 19 and 20" wheels and they look good but I can imagine how rough the ride is with no sidewall. I think these Enkei's will do for now so I can experiment with tire sizes and see what will fit.
 
1 - 12 of 12 Posts
Top