1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Wheel fitment

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Old Mar 6, 2021 | 05:03 PM
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From: nc
Wheel fitment

Before I start I know this question has been brought up 100000000042069 times. I have searched and read but the information seams to get mixed up between the 12a gsl and 13b gslse, now I am confused on what will fit and what wont.
I have a 1981 gsl, I want to run 15x7 rpf1s with 1 inch wheel adapters . What offset do I need to fit in the stock fenders with stock suspension? They have 15x7 with 35 and 41 offsets, I would also settle for 14x7 in 19 or 28 if that would work with a 1in inch 4x110 to 4x100 adapter. Would consider the 16 as well
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Old Mar 6, 2021 | 07:43 PM
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What's the advantage of running a spacer?
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Old Mar 7, 2021 | 02:16 AM
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Most people get 15 x 7 with 20mm offset, 4x110 and 195 or 205 width tires (205/50 r15). Those RFP1's are nice wheels but I don't know what specs you'll need to fit them with a bolt circle adapter / spacer. There are other style Enkeis though that do come in 4x 110. Rota makes several styles too (I like their Shakotans) or Panasports.

Last edited by Maxwedge; Mar 7, 2021 at 05:33 AM.
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Old Mar 7, 2021 | 05:07 AM
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From: nc
Originally Posted by KansasCityREPU
What's the advantage of running a spacer?
the 4x100 bolt pattern
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Old Mar 7, 2021 | 05:11 AM
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Originally Posted by Maxwedge
Most people get 15 x 7 with 20mm offset, 4x110 and 195 or 205 with tires (205/50 r15). Those RFP1's are nice wheels but I don't know what specs you'll need to fit them with a bolt circle adapter. There are other style Enkeis though that do come in 4x 110. Rota makes several styles too (I like their Shakotans) or Panasports.
I will look at the Rotas, I'm wanting something that isn't a mesh or a Panasport wheel. Nothing against them just want something different.
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Old Mar 7, 2021 | 05:21 AM
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From: nc
Originally Posted by 1st_gen_rx7
Before I start I know this question has been brought up 100000000042069 times. I have searched and read but the information seams to get mixed up between the 12a gsl and 13b gslse, now I am confused on what will fit and what wont.
I have a 1981 gsl, I want to run 15x7 rpf1s with 1 inch wheel adapters . What offset do I need to fit in the stock fenders with stock suspension? They have 15x7 with 35 and 41 offsets, I would also settle for 14x7 in 19 or 28 if that would work with a 1in inch 4x110 to 4x100 adapter. Would consider the 16 as well
With a 1 inch adapter (25.4mm) 15x7 with 41 offset I should have 15.6mm offset to the hub. Will that fit or am I thinking wrong?
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Old Mar 7, 2021 | 07:30 AM
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Originally Posted by 1st_gen_rx7
With a 1 inch adapter (25.4mm) 15x7 with 41 offset I should have 15.6mm offset to the hub. Will that fit or am I thinking wrong?
Yes , this is correct. and that should fit no problem. the 38 would work as well approx 12mm offset just poke out a little more...
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Old Mar 7, 2021 | 08:20 AM
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So the 15x7 Konig Rewinds have a 20 offset and they fit just right. So just do the math to get your spacer thickness. Personally wouldn't use a spacer but I've seen it done before.
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Old Mar 7, 2021 | 10:45 AM
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Originally Posted by lwrobins
Yes , this is correct. and that should fit no problem. the 38 would work as well approx 12mm offset just poke out a little more...
Thank you for the help.
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Old Mar 7, 2021 | 10:47 AM
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Originally Posted by t_g_farrell
So the 15x7 Konig Rewinds have a 20 offset and they fit just right. So just do the math to get your spacer thickness. Personally wouldn't use a spacer but I've seen it done before.
not the biggest fan but its better than using wobble bolts on 4x108 wheels. Big trucks use them all the time my shitbox should be safe with them.
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Old Mar 7, 2021 | 07:43 PM
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The advantage offered by 4x100mm wheel is greater variety and they are lighter than 4x110mm and 4x114.3mm wheels. So i converted my RX7 using a 25mm adapter spacer on the front and by having my GSL axles drilled to 4x100mm. This is on a race car and I run 15x8" with a 35mm offset Kosei wheels for dry tracks. My rain wheels are 15X7 with 25mm offset. I have rolled fenders and my car is about 3.5 inches lower than stock.

What I found when I did this is that the rear axle is wider than the front when I measured from hub face to hub face at ride height. So I really only needed spacers on the front. I ended up running the 25mm adapter + 10mm spacer so that the front wheels have a 0 offset. On the back I use a 5mm spacer to keep the tires from rubbing on the suspension on the driver's side which means the rear has an effective offset of 30mm. Allot of this is because of the way Hoosier racing tires are made. With 205/50 15 street tires you might not need that much spacer on the front.

I don't really like running spacers either because they add weight and it is one more thing to check and keep tight. But they work and are safe as long as you make them hub centric because that takes the side load off of the studs. I had the ones I have made by a machinist I trust because that way I knew the material being used and that the studs are from ARP.



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Old Mar 8, 2021 | 05:02 AM
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Originally Posted by mustanghammer
The advantage offered by 4x100mm wheel is greater variety and they are lighter than 4x110mm and 4x114.3mm wheels. So i converted my RX7 using a 25mm adapter spacer on the front and by having my GSL axles drilled to 4x100mm. This is on a race car and I run 15x8" with a 35mm offset Kosei wheels for dry tracks. My rain wheels are 15X7 with 25mm offset. I have rolled fenders and my car is about 3.5 inches lower than stock.

What I found when I did this is that the rear axle is wider than the front when I measured from hub face to hub face at ride height. So I really only needed spacers on the front. I ended up running the 25mm adapter + 10mm spacer so that the front wheels have a 0 offset. On the back I use a 5mm spacer to keep the tires from rubbing on the suspension on the driver's side which means the rear has an effective offset of 30mm. Allot of this is because of the way Hoosier racing tires are made. With 205/50 15 street tires you might not need that much spacer on the front.

I don't really like running spacers either because they add weight and it is one more thing to check and keep tight. But they work and are safe as long as you make them hub centric because that takes the side load off of the studs. I had the ones I have made by a machinist I trust because that way I knew the material being used and that the studs are from ARP.
This is the info we need. I do like the thoughts of having 8s in the back. I can make that happen. Thank you for the info.
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Old Mar 8, 2021 | 10:16 PM
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Anyone have pics of a 1st gen with rpf1s? I’ve never seen it done!
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Old Mar 9, 2021 | 05:12 AM
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Originally Posted by cmnork
Anyone have pics of a 1st gen with rpf1s? I’ve never seen it done!
Exactly why I want a set. That and my car is ratty enough it would be funny to have a really nice set of wheels on it.
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Old Mar 10, 2021 | 08:44 AM
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Like Scott, I use 25mm spacers on my racecar. I have had one failure. That occurred when I somehow managed to only install 3 of the lugnuts holding the spacer to the front hub. Otherwise no issues at all.

With Hankook Rs4's, 225-45-15 and Toyo RR, 205-50-15 I can use ET30 to ET40 (Team Dynamics ET30 and ET40 and Kosei ET38). With 205-50-15 Hoosiers, the ET40 tires rub slightly on the 2.5" coilovers. ET30 pushes the tires out to the edge in front with flattened (take of the front fender and flatten the lip with a rubber mallet) lips. A bit more room in the rear. No rubbing either end though.

I like the adaptitusa adapters, because they attach with "shouldered" lugnuts, that seem to support the spacers more positively than cone type lugnuts.

Good luck.

Carl

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Old Mar 10, 2021 | 09:33 AM
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Originally Posted by Carl
Like Scott, I use 25mm spacers on my racecar. I have had one failure. That occurred when I somehow managed to only install 3 of the lugnuts holding the spacer to the front hub. Otherwise no issues at all.

With Hankook Rs4's, 225-45-15 and Toyo RR, 205-50-15 I can use ET30 to ET40 (Team Dynamics ET30 and ET40 and Kosei ET38). With 205-50-15 Hoosiers, the ET40 tires rub slightly on the 2.5" coilovers. ET30 pushes the tires out to the edge in front with flattened (take of the front fender and flatten the lip with a rubber mallet) lips. A bit more room in the rear. No rubbing either end though.

I like the adaptitusa adapters, because they attach with "shouldered" lugnuts, that seem to support the spacers more positively than cone type lugnuts.

Good luck.

Carl
Wow thanks for the info. Its amazing how friendly everyone is with wheel questions, god forbid you have a boost or engine management question though. Thanks to all the good info everyone. Hopefully this helps other people too.
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Old Mar 10, 2021 | 09:37 AM
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I would add that one of my goals was to be able to rotate tires/wheels front to back because the gets the most life out of a set of tires during a season. My other goal was to take advantage of wheels made for a more popular car - the Miata. I mean spend some time on www.good-win-racing.com or www.tirerack.com and see what is out there with respect to Miata wheels. The math worked out that a +35mm offset 15x8 wheel is the easiest for me to work with but I could probably make a +28 or +25 wheel work.

To save weight on the front I have considered ditching the spacers and using 0 offset 4x114.3 wheels but it would mean that I have dedicated front and rear tire/wheel packages. I could still rotate front to back but it would mean visiting the tire guy at the track more often.

Here is a shot of the car. I was running 225/45x15 Hoosiers on the rear and 205/50x15 Hoosier SM7s on the front.


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Old Mar 10, 2021 | 12:43 PM
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Oh right. I forgot to mention that my wheels are all 15x7. Kind of important when talking "ET".

Carl
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Old Mar 12, 2021 | 06:54 AM
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8x15


8x15 175/55/15 JNC wheels

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Old Mar 12, 2021 | 07:02 AM
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That looks awesome Manny! Someone in another thread was wondering what Enkei RPF1's would look like on a 1st gen. With a similar design, your rims look awesome. I especially like the two-tone w/Gold.
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Old Mar 16, 2021 | 08:22 AM
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Originally Posted by cmnork
Anyone have pics of a 1st gen with rpf1s? I’ve never seen it done!
Found this on FB


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Old Mar 16, 2021 | 10:09 AM
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Originally Posted by 1BADRX7
Found this on FB

thanks! i think i prefer period correct rims...
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