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  1. #1

    Default 15x7 and 15x9 for 1985 foxbody

    Hi, guys. Thinking about changing out my wheels for my 1985 foxbody GT. This is what I want to buy:

    15 x 7s for the front

    -Offset 22.5
    -backspace 4.89

    15 x 9s for the back

    -offset 18
    -backspace 5.71

    I tried to look through some of the other posts, but I don't know a lot about cars and couldn't make sense of much that was being discussed. I guess my questions are what size tires I should get and will the mechanic have to make any modifications to the suspension or use spaces, etc. Thank you in advance!

  2. #2
    Moderator wraithracing's Avatar
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    Before getting into the size and offsets of said wheels. Are you sure you want to stay with 15"? The reason I ask is that there are not many "performance" options left in 15" tire sizes. You have a much larger variety of options in both 16" and 17" tires compared to what is available for15" these days.

    If you are already set on what type of tires you want to run in 15" and are good with the choice that's cool! I just bring it up because I have swapped out 15" for 16" even on my essentially stock 82 RS due to the lack of tire options in 15".
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
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    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
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    1981 Capri Roller
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    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
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  3. #3
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    Wraithracing good point ! I have an Oldsmobile with 15 inch rims / tires . i agree not much good selection in 15 inch . I was also thinking about changing rim size to have a better selection of tires . The only reason i keep going with 15 inch is i already have hard to find and sought after 15 inch rims on the car . OP , you could look at Diamond back tires and Coker tires to see if there is a tire in 15 inch that you like before getting 15 inch rims .

  4. #4
    Moderator wraithracing's Avatar
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    There are still 15" tires, but just not a lot of options in the standard Foxbody 225/60/15 The BFG option are nice, but the molds are old and the tires tend to be a hard compound that doesn't provide a lot of grip. Some have had issues with treadwear chunking over the years. Most other options are going to be more all season typical commuter type tread design and compound. Nothing wrong with that for the typical cruiser/weekend play toy, just depends on what you want to do with the car. I also get rare or cool looking wheels in the 15". Many will have a set of those used for shows, etc. and then a different set in 16" or 17" that are more driver type wheels and tires.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  5. #5
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    OP asks about suspension modifications with a different tire size . Any car going to a larger rim size , is a stiffer ride . Larger rim less tire side wall . OP how do you like the ride of the car now with the tires you have . This is a personal choice . Maybe you or a family member will not like a stiffer ride . Our Capri with 14 inch rims, family says rides like a go cart . So my family says no to larger rims . One other thing to think about is a spare tire , and will it match the tire size you are thinking of changing to . A good spare can do hyway speeds .

  6. #6

    Default

    This is a great site for calculating the impact of different tire/wheel sizes and ET/BS.
    https://tiresize.com/wheel-offset-calculator/
    I also referred to LMRs wheel guidelines to get base setups that fit and then us3d calculator to see if combos I was looking at fit the same as LMR setups.
    I’d be thinking 17s minimum given the state of 15 inch tire availability.
    i ended up with 18s.
    Steve

    1983 Mustang GT
    Popular Hot Rodding Project Car '83/84

    1983 Capri 331 ci, TKO600

  7. #7

    Default

    Quote Originally Posted by wraithracing View Post
    Before getting into the size and offsets of said wheels. Are you sure you want to stay with 15"? The reason I ask is that there are not many "performance" options left in 15" tire sizes. You have a much larger variety of options in both 16" and 17" tires compared to what is available for15" these days.

    If you are already set on what type of tires you want to run in 15" and are good with the choice that's cool! I just bring it up because I have swapped out 15" for 16" even on my essentially stock 82 RS due to the lack of tire options in 15".

    Thanks for your reply. Well, I want to keep things original as possible, and I really like the 10 hole wheels, and I wanted something staggered. LMR has the 15x9s and 15x7s in the 10 holes.

  8. #8

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    I respect what your saying, but 16" would hardly be noticeable and would look nicer..... Has some friends do this to their 60's/70's muscle cars..

  9. #9

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    Quote Originally Posted by Bentley View Post
    I respect what your saying, but 16" would hardly be noticeable and would look nicer..... Has some friends do this to their 60's/70's muscle cars..
    Do you still have the 4 lug? I would change that first......

  10. #10
    Moderator wraithracing's Avatar
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    Quote Originally Posted by cnoll76 View Post
    Thanks for your reply. Well, I want to keep things original as possible, and I really like the 10 hole wheels, and I wanted something staggered. LMR has the 15x9s and 15x7s in the 10 holes.
    Not to be a jerk or anything, but what you really want is something that looks "Stock" or has the "Stock Look". "Original" would be the original OEM 10 holes and not a staggered setup of 10 holes. I only mention this as it helps others understand what you are trying to achieve with your choices. "Original" really means the way it was originally built and delivered by Ford. "Stock Looking" gives the average person the impression that it is original and stock, while more knowledgeable enthusiasts will know and appreciate the small subtle changes that you have made.
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  11. #11
    FEP Senior Member Patrick Olsen's Avatar
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    Quote Originally Posted by wraithracing View Post
    Not to be a jerk or anything, but what you really want is something that looks "Stock" or has the "Stock Look". "Original" would be the original OEM 10 holes and not a staggered setup of 10 holes. I only mention this as it helps others understand what you are trying to achieve with your choices. "Original" really means the way it was originally built and delivered by Ford. "Stock Looking" gives the average person the impression that it is original and stock, while more knowledgeable enthusiasts will know and appreciate the small subtle changes that you have made.
    https://www.youtube.com/watch?v=pWdd6_ZxX8c

  12. #12
    Moderator wraithracing's Avatar
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    Quote Originally Posted by Patrick Olsen View Post
    Name:  Agree with you!.jpg
Views: 75
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    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  13. #13
    FEP Senior Member OX1's Avatar
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