This is topic Run 205/50/15 RA1's on OEM 15x6 wheels? in forum Spec Miata Competition Tires at Spec Miata Community.


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Posted by TR6 (Member # 16732) on :
 
My son just bought a 1990 miata for DE with a plan to eventually finish building it out to SM (it is halfway done). The car is still street legal and he will drive it to the track. His only set of wheels right now are the OEM 99+ 15x6 wheels. Can he run the spec 205/50/15 RA1's on them without any problems due to the width of the tire? Meanwhile I'm trying to find him an extra set of cheap 15x7 SM wheels. I have found two of the older style Team Dynamic "Ben Hurr" wheels (with protruding spokes) but need to find two more to make a complete set for him.
 
Posted by Kyle Keenan (Member # 4018) on :
 
A racer here in the NW has his rains mounted on his OEM 99+ wheels, and hasnt had any major problems with doing so!
 
Posted by NER88 (Member # 489) on :
 
I have to run 15X6 oem wheels on my SSB Miata.
The 205/50/15 Toyos work and fit just fine but they are not legal for SM.
You don't have to match the TD wheels as long as the other two wheels have the same offset.
 
Posted by Ron Alan (Member # 23433) on :
 
quote:
Originally posted by NER88:
I have to run 15X6 oem wheels on my SSB Miata.
The 205/50/15 Toyos work and fit just fine but they are not legal for SM.
You don't have to match the TD wheels as long as the other two wheels have the same offset.

To clarify...the 205's fit fine on the 6". The problem for SM is they are to light I believe...must be 13 lbs min.
 
Posted by Joe Specht (Member # 3263) on :
 
The recommended rim width for the 205/50R15 Toyo RA1 is 5.5 to 7.5. The tire is fine on a 6" wide wheel. To race in Spec Miata the wheel must be 15X7 and at least 13 lb, also I believe that all 4 wheels must be of the same type and offset.
For a DE it doesn't matter what you use.
Joe
TreadZone
 
Posted by TR6 (Member # 16732) on :
 
Thanks everyone, it sounds like it will work fine. He will just be DE'ing the car for a while. He is a fresh college graduate with no real money to speak of but has already become addicted to the track! His plan is to buy a set of full tread RA1's and run them on the 15x6 wheels for HPDE and also use them to drive to and from the track. As I mentioned, in the meantime I am scrounging around for some used SM wheels (I've already found a pair of the older TD wheels with 30mm offset).

Joe, I'm pointing him to Treadzone for the tires. You guys do a great job and I've been very pleased with your service on the tires I've gotten from you.
 
Posted by Kyle Burkhardt (Member # 26745) on :
 
I plan to run stock 99s on my SM til I have the funds for new wheels.

miata.net lists them at 13.1, and we weighed one last week to confirm that they were 13+.

As to width, as I understand it, 7 inch is not required, its just the max, so there should be no reason I can't run 6's. I'm in NASA if that matters.
 
Posted by rmgroth (Member # 18748) on :
 
quote:
Originally posted by Kyle Burkhardt:
I plan to run stock 99s on my SM til I have the funds for new wheels.

miata.net lists them at 13.1, and we weighed one last week to confirm that they were 13+.

As to width, as I understand it, 7 inch is not required, its just the max, so there should be no reason I can't run 6's. I'm in NASA if that matters.

The NASA rules state that 7inch is the maximum, so you are fine on 6's but you will probably be giving up some grip.

The TRMotorsports wheels are only $75 each and hold up well.
 
Posted by Kyle Burkhardt (Member # 26745) on :
 
The MW SM GP ("Grand Pubah") has spoken!

Dude, I'm still selling off spare parts to buy a seat for the car. I don't have the $$$ for new wheels!

Plus, I always build into my cars a built in excuse. Usually two or three.
 
Posted by John Hammer Palazzolo (Member # 743) on :
 
I've run for years on a 15x6.5 wheel & it was just fine...and legal, if not optimal.
 
Posted by motorrock (Member # 15080) on :
 
quote:
Originally posted by rmgroth:
quote:
Originally posted by Kyle Burkhardt:
I plan to run stock 99s on my SM til I have the funds for new wheels.

miata.net lists them at 13.1, and we weighed one last week to confirm that they were 13+.

As to width, as I understand it, 7 inch is not required, its just the max, so there should be no reason I can't run 6's. I'm in NASA if that matters.

The NASA rules state that 7inch is the maximum, so you are fine on 6's but you will probably be giving up some grip.

The TRMotorsports wheels are only $75 each and hold up well.

The TR Motorsports Spec Miata wheel is $89.
 
Posted by Will Dodd (Member # 27809) on :
 
It sounds like I'm in the exact same position as your son. I graduated college in '08 and now that I have a steady source of income my dad and I have been doing increasingly more HPDE's each summer.

But in any case, I run 205 Hoosier R6s on the 99+ wheel and it works just fine.

Next year though I'm planing on going with 949Racing 6UL 15x7.5 w/ 205s as street/STS autocross tires and for the track some SM wheels with RA1's. I'm looking forward to seeing what the different is.
 
Posted by JC-MX5 (Member # 27578) on :
 
quote:
Originally posted by rmgroth:
[QUOTE]The TRMotorsports wheels are only $75 each and hold up well.

From where?