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Finally got my new 18s in. Brought them up to work and installed them today. Everything went pretty well, except one wheel that didn't want to cooperate balancing. We have a really high end Hunter balancer, and I was roadforce balancing them. One wheel kept showing a possible bent assembly and was showing extremely excessive road force numbers. I was able to get the roadforce down to a slightly high, but acceptable level, and get it balanced, but it took a good amount of weight. I'm thinking this may actually be a bad wheel, I may have to push for a replacement.
As far as fitment, my painstaking/OCD measuring paid off, the wheels fit great. Here's what I went with:
Front: 18x9.5 with 4.75" BS
Rear: 18x10 with 5.25" BS
Tires are Continental Extreme Contact sport
Front: 275/40
Rear: 285/40
Front suspension is Vansteel coilover, rear is VBP mono spring with offset trailing arms.
Check out my previous posts for my calculations on how I chose these sizes. I was pretty precise and it paid off, they fit perfect. Thanks to everyone who helped figuring it out!
Before
your 80 blows the old argument out about the chrome bumper cars looking way better than the rubber bumper cars !! Beautiful
Are you sure your working is correct as my workings make the Tire on an 8" rim having 9,6" of tread on the road and not 8.6??
That diagram shows 8.0" of tread width, and 9.6" of sidewall width.. And an 8.0" wide rim. Did you type those numbers in or did the software program supply them for you?
I got my measurements from Tire Rack online. They give accurate measurements in the spec section. A 245-40-18 Michelin Pilot Sport all season is listed there with a 25.9" dia, and 8.5" of tread width . The mfgr recommended rim widths are between 8.0" and 9.5". You must stay between these widths or you will have trouble with the tire bead sealing or undue stress on the sidewall.
They give a sidewall width of 9.8" when mounted on a 8.5" rim. The measuring rim width is the absolute smallest I would recommend for any tire. My main point in the post is that if you push the rim width out to the maximum recommended width (9,5" in this case), the sidewall are much more vertical and there is at least 1" less horizontal movement of the tire on the rim in a hard turn. So the tire responds much more crisply when you turn the wheel. It feels so much better to drive! There is less lag-time for the tire to take a set. And especially at the limit of adhesion at max G-force when you try to make small course corrections mid-turn. This is race car tuning, and it has been proven for years. I experienced it myself on my maximum effort Pro-Solo car. It felt like 2-3" of "slop" disappeared from the steering wheel, (I had a 2" width increase with the same tires.) The steering wheel became a razor sharp precision "scalpel" and I could feel very small 1-2 degree inputs, or 1/8" - 1/4" at the steering wheel. afterwards. And it generated more G-force, and I had to re-adjust my tire pressures (lower) and change the alignment (less negative camber) to keep the tire temperatures consistent all the way across the tread (at 1.25G).
The tire size does not really change much. If you keep the wheel offset the same the tread does not move at all. (It means the rim backspacing needs to change by half) The sidewall does grow a little bit. BFG says it is 0.2" of sidewall growth for every 0.5" of increased rim width over the "measuring" rim width. So in the case above the sidewall would grow 0.4" from 9.8 to 10.2" by going from a 8.5" wide rim to a 9.5" rim. It is really not a big interference problem because the tire sidewall now moves less in a turn anyway. So it probably winds up in exactly the same position when flexed.
Regardless I would always recommend to try to keep at least on inch sidewall clearance from hard steel parts (when still). You can however go much closer on the rim because it does not flex. I ran my 10.0" wide front rims on my 1970 Z28 1/8" away from the ball-joints, a-arms and sway bar. Never touched. But I did have to use stick-on weights not clip-on. There was no room for clip-ons! LOL
Last edited by leigh1322; Aug 4, 2020 at 08:53 AM.
Front and Rear: 18x8.0 with 4.00" BS Tires are Goodyear Eagle F1 235/50
What are those wheels !!!!! WOW, that's the best looking Ralley (looking) wheel I have ever seen.... The center caps with the wheel are a perfect size......
Can you please add more pictures? I would love to see what this looks like from behind.
Last edited by mitch.1972vette; Aug 4, 2020 at 10:53 AM.
Reason: Additions to my statement...
I can confirm based on my car. I did a test fit with 18x10, 5.5 bs. Totally stock front end had no issues other than if you really crank the steering, the 285/35s will rub. I tried in the rear with the VB&P dual mount spring and stock sway bar. The wheel cleared the spring(barely) but did lightly hit the sway bar. The parking brake tab would need to be relocated as others have said. I then changed to Van Steel's front and rear coil over set up, but I did the test fit with the above suspension. There is probably room for another 1/8-1/4 inch of front side but I didn't want to push it and risk fiberglass interference. The pic below is with -1.0*front camber and -0.7* rear camber. Due to production tolerance, the passenger side front is about 1/8 close to the tire than the driver. It's like the body needs to move about 1/16" to the right. Remember, these cars are 50 years old and ancient production tolerances, combined with wear, tear and unknown repairs over the years might make yours fit slightly different than mine.
Thanks. They are Rocket Racing wheels. Rocket Attacks. 18x10 The tires are Nankang N2-SR's. 285/35r18. The tires are pretty sticky 200TW tires. Phil's Tire Service is the best place I found for them.
Hello Jimco.....My tire guy says no 285's? are you sure of the size? just want to make sure I am getting the right tire.
Absolutely positive. Try these guys. They have them in stock (as of yesterday anyway) Give them a call. You'll find Kim and Phil both to be quite knowledgeable about performance tires. https://philstireservice.com/shop/nankang-ns-2r/
Absolutely positive. Try these guys. They have them in stock (as of yesterday anyway) Give them a call. You'll find Kim and Phil both to be quite knowledgeable about performance tires. https://philstireservice.com/shop/nankang-ns-2r/
I ordered American Racing wheels. I have Borgeson Steering. Wheels rub on sway bar, no tires mounted yet. So I am not sure I can go with the 18x10 5.5bs on the front. any ideas? I have a 1981, didn't think year would make any difference how wheels and tires fit?
Not sure honestly. You do mean rubbing the front sway bar, right? I rubbed the stock rear bar, but am running without one now that I have the coil overs. I don't rub the sway bar. I get a rub on the bolts for the steering box(borgeson also), and about the same place on the passenger side frame if I really crank the wheel. I was at Sebring this past weekend and it did lightly touch the paint in the rear inner fender. Stock sway bar?
I'm like you, I wouldn't think they would rub on yours if they fit on mine. Maybe the American Racing lips are different or thicker? Don't mount tires yet...If you want, send me some pics of the test fit and I'll compare to mine. jimco84 at gmaildotcom
Yes...it hits the front sway bar. I looks like the tire will get chewed on the bumper bracket. I know these Wheels will fit on the rear after I move the E brake cable (doing that this weekend. So I am going to have 2 tires mounted and take a look at clearances that way on the front. I may have to modify my bumper bracket on my car. I will let you know what I come up with. thank you for the help!
After many months of reading, looking and indicision I finally have my setup, Specs: US Mags Rambler U110 Chrome Classic 18x8" ET1 shipped with Mitchlin Pilot Sport 4 245/45 ZR18 100Y
Before ....
...and After
and although I loved the old look, I Love the new look now much more.
Beautiful!!! Any issues with the wheels fitting? Did you order wheels and tires together? Any suspension mods?
I'm thinking of going with the same combination for my 69 350 coupe.
Originally Posted by mysticpete
After many months of reading, looking and indicision I finally have my setup, Specs: US Mags Rambler U110 Chrome Classic 18x8" ET1 shipped with Mitchlin Pilot Sport 4 245/45 ZR18 100Y
Before ....
...and After
and although I loved the old look, I Love the new look now much more.
Beautiful!!! Any issues with the wheels fitting? Did you order wheels and tires together? Any suspension mods?
I'm thinking of going with the same combination for my 69 350 coupe.
So the wheels and tires were all ordered at the same time from a dealer here in Australia and the tyres were a very good price, there's no mods required to the car at all but remember the wheels will sit in half an inch so you may want to get spacers for them, they are illegal here in Oz except on track cars.
