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

Fat tire, skinny wheel

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Old 10-18-07, 07:04 AM
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Fat tire, skinny wheel

I'd like to try to fit a 205/60HR-13 tire onto the stock 5.5" rim of my 1983 RX-7 GSL. Does anyone know if this will work?
Old 10-18-07, 08:12 AM
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A few of us are actually running 215/50/13 Sumitomos on the stock "plus" wheels. I have had no issues with fitment. I had the 205s first time around, so either way you should be fine...
Old 10-18-07, 08:17 AM
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I've run this size for 20 years on my SA, no problems other than finding tires this size now. I may go to 195s to get a decent performance tire.
Old 10-18-07, 08:32 AM
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The Sumitomo HTR 200 from Tire Rack was actually was I interested in purchasing. Sorry, but what is a stock "plus" wheel? I have stock "four spoke" rims.
Old 10-18-07, 08:57 AM
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the 4 spoke is the "plus" rims or "+" if you will

but i didnt know 215's would fit, WOOHOO, Im going tire shopping, I'm running the sumitomo's now, love them, they are grippy in wet or dry situations and cheap!
Im running the 205/60/R13's
Old 10-18-07, 09:46 AM
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Thank alot for the help!
Old 10-18-07, 09:52 AM
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can you guys with the 215/50's post a pic so i can get an idea of the look? I like they way the 60's fill the wheel well. Thanks
and i have the 1" drop Eibach springs on all 4 corners.
Old 10-18-07, 10:00 AM
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The 215s are slightly smaller in diameter than the 205s. This results in a larger wheel gap (slightly), and throws off the speedometer about 4mph @ 70 (estimated). However, the car feels a little "zippier" due to the reduced drive ratio. On the car, they look pretty beefy.
Old 10-18-07, 11:08 AM
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factory put 205-60-14's on the gsl-se wheels, which are 5.5" too, so 205 is fine...
Old 10-18-07, 12:00 PM
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yes, you'll be fine with 205s. i, personally, won't run anything less.
Old 10-18-07, 09:09 PM
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Originally Posted by johnfoothill
I'd like to try to fit a 205/60HR-13 tire onto the stock 5.5" rim of my 1983 RX-7 GSL. Does anyone know if this will work?
bro, you can fit 235-50-13 on the stock rims
Old 10-18-07, 09:53 PM
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Originally Posted by t_g_farrell
I've run this size for 20 years on my SA, no problems other than finding tires this size now. I may go to 195s to get a decent performance tire.
i thought 205/60/13 would rub on the front of an SA with the 5.5" rims? am i wrong then? Also wouldn't the 205/60/13 sides walls flex to much? i was just going to go 195/60/13
Old 10-18-07, 10:41 PM
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Originally Posted by Kentetsu
The 215s are slightly smaller in diameter than the 205s. This results in a larger wheel gap (slightly), and throws off the speedometer about 4mph @ 70 (estimated). However, the car feels a little "zippier" due to the reduced drive ratio. On the car, they look pretty beefy.
I don't understand why the speedometer would be off... doesn't the speedometer cable run directly from the tranny? And if it does cause a poor reading, what would 17" rims with those like 1" sidewalls do? O.o
Old 10-21-07, 11:15 PM
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tire fitment

Will 215/50-13's also fit on either the "keyhole" or "waffle" wheels on an SA?
Old 10-21-07, 11:23 PM
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Man I run 215/45/16 on my aftermarket rims with no clearance problems.

Speedometer is off because the outside diameter of the tire changes, changing the gearing ratio that the transmission attached cable reads. It means the tire takes less distance (assuming a smaller tire outside diameter) to complete a full revolution while the speedo reads one revolution at the stock sizing, my set up is within 1% of the stock set up which tire wear can account for more than that

A quick break down of tire sizing is

205 width of tire section in millimeters
45 percentage of tire section width ie 45% of 215 or 96.75mm
16 rim diameter in inches
Old 10-21-07, 11:51 PM
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Thanks for the Speedo lesson, I always wondered about that.

BTW I found this in another thread,, its pretty useful fo figuring tire sizes and such...
http://www.miata.net/garage/tirecalc.html

I'm thinking of running 205/40/17 Falken F452's with a Kobe or Enkei Rim in the future and its nice to know that they will fit the wheel well the same as my stock 185/70/13 Plus Rims do. (a 1.1% diff, not bad at all)
Old 10-22-07, 01:37 AM
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They'll fit, but won't perform as good as intended when pushed hard, especially at a track day. 5.5" rims should run /175-185's
Old 10-22-07, 09:15 AM
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205/60/13 tires

I know you have the answer already. I autocross on used Formula Ford Hankooks 205 60 13's. When the inside tread wears, I reverse them. Seems to work well as long as the rotation direction is maintained.
Old 10-22-07, 10:54 AM
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I run 215/60-14 on my GSL-SE rims even though they are wider than recommended, but they work just fine.
Old 10-27-07, 01:29 AM
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SA tires

So does anyone know if 215/50-13 tires will fit and clear the SA strut on either "keyhole" or "waffle" wheels?
Old 10-27-07, 11:33 PM
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they fit

I mounted a 215/50-13 BF Goodrich R series tire on a "waffle" wheel to check the fit.
It works with no issues on my 1979 SA in the rear and about 0.2 " clear from the spring perch on the front. Looks like a 60 series might put the tire bulge further out (due to the larger diameter) and may result in need to grind the spring perch for clearance.
Hopefully this will be at least one data point with "real data" in all the hundreds of threads with no clear answers.
Old 10-28-07, 02:56 AM
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my 205/60-13 sumitomos rub in the front. I am running ground control's coilover setup and the tires are rubbing on the springs.
Old 10-29-07, 01:39 PM
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This is my car with the Sumitomo 215/50/R13 HTR200, I havent had any problems with fitment. When I went Tire shopping I was actually looking for the BF Goodrich TA tire in this size but there no longer available
Attached Thumbnails Fat tire, skinny wheel-1980-mazda.jpg  
Old 10-30-07, 03:03 AM
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Now I am convinced. I'll order the 215's this week. Your car is clean!
Old 10-30-07, 08:24 AM
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Thanks. She is my pride and joy, she will never see rain or snow and limited use on Sundays. Of course she will make the local car show rounds. As for the tires I had them for last 4 months and driven the car about 300 miles and they have never rubbed. Now my car is completely stock including suspension.

Last edited by NR74; 10-30-07 at 08:33 AM.




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