Diamond Wheels

R

rx7chris

New member
I'm thinking about getting a set of diamond wheels for my 83 RX7 IT car. What sort of backspacing do i need. I was planning on getting 13x7's, is that too big? If not what size tire can i run, without substantial rub? On a second note, has anyone tried the new Kumho Ecsta v700's? They come in some sizes that look pretty good (on paper) for the RX7, like 215/45's might be a 50 series. I'm looking for a compromise between outstanding grip and longevity. Most bang for the buck. The Grasroots test (old one) made it look like the Kumho's were almost as fast as hoosier's. Whats the consensus of the group?

Thanks in advance,
Chris
IT7 #88
PowerTrip Racing
 
rx7chris,

go to general discussion for diamond wheel topics, I included info on backspacing for 1st gen rx7. I don't have any info on new Kumho's.

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Daryl DeArman
I Love RX7's...they taste like chicken :P
 
Chris, I'm running Diamonds on my IT-7. 13x7, 4 inch backspace. I'm assuming you have coilovers on the front, otherwise you might have a clearance problem.

Ed
 
If the "Diamond" wheels you are speaking of are the steel wheels-----a note of caution---a buddy of mine ran a set of 13X7 steel wheel on his IT-7----the wheels had the extra reinforcement plates welded on the back (from the factory) and 3 of 4 of the wheels have developed stress cracks associated with the weldsof the reinforcement plates-----don't recall if they were "diamond" wheels---but if your wheels have this reinforcement plate----check them often for cracks. The unreinforced wheels (on a car that I have been sharing with a friend) seem to be doing better---i.e. no cracks---and they have seen much more track time than the "reinforced" wheels. Just one racers experience.
 
In as far as Diamond wheels go, I agree with Lee. I run 13" x 7" Diamonds with a 4" back space. (no reinforcing plate) and have had tremendous service from them. Balancing is easy and they take very little weight. To locate them go to www.diamondracingwheels.com or call Chris nt Racecar Engineering at 407-629-7400. You will find they are cheaper than Panasports (by a lot) and they are only 13 lbs. each. If you bend one it doesn't hurt when you have to replace it. Note: Make sure you get the correct lug nuts for these wheels as they use a 45 degree face instead of the normal 60 degree face.
 
Lee, the steel wheels with the backing plates are made by FastWheel and they're much heavier than the Diamonds. The Diamonds are a real bargain and seem to work quite well.

Ed
 
Thanks for the info on the wheels, i'm gonna get the mini stock's with a 4 inch back space. the way it sounds, they'll clear my ground control suspension.

Waht about rubber? What are people running, I know alot of guys are running Toyo's. I plan on running 5-6 events this year, all in the CFR. For that amount of races what would be a good tire to go with? I'd like to buy only one set of tires for the year, if its possible.

Thanks again,

Chris
IT7 #88
PowerTrip Racing
 
Chris,

I also run a ITA/7 RX-7. I use the wheel studs you get from Mazda Comp. Do you remember the thread size for those studs? Is it 12mm? I am thinking about buying a set of Diamond wheels for my rain tires. I don't want to have to change the studs to use the new wheels.

Any info will be greatly appreciated.

Thanks.

Drive Well
 
Festus, yup they are 12x1.5 mm. I use 2 inch long or 51 mm or what ever they are # 0000-04-7901.



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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
yeah festus 12 x 1.5mm. i use the screw in studs in the front and press in's in the rear. i ended up getting my studs for free, mazdacomp forgot to bill me. be sure to check them often, and use loctite always on the stud itself, not the lug nut.

What about tires? Anybody?

Chris
IT7 #88
PowerTrip Racing
 
I'd try the Kumho Victoracers. Depending on track condition, how fast you are, how much time those 5-6 events equates to, etc., they may not last that long. But I don't know of another DOT Race tire that will last longer (toyo?)

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Daryl DeArman
I Love RX7's...they taste like chicken :P
 
I have used Hoosier, Toyo, and Kumho. I never could get quicker on the Hoosier than I did on the other two. However, that was a couple years ago and I think seat time has a lot to do with it. When I talked to a couple guys about the difference in the tires this is one of the answers I got. The waar issue aside.

Hoosier - Fast from the very beginning. You can take the first turn on the start at full race speed.

Toyo - If you scrub them VERY VERY hard during the warm-up lap you can almost go full race speed in the first turn on lap one. They will take about one half to a full lap to get up to temp.

Kumho - No matter what you do it takes 2 - 3 laps to get them up to temp. (Victor 700s)

In my experience this is pretty much right on.

I am interested in the new Kumho 235 X 13. A seven inch rim is a little small for them (about one half inch). The 215 X 13 Kumho may be the way to go.

When I use up my current tires I just have to see.

Hell, I'm so old and slow I need all the help I can get.

Drive well
 
I used the 205/60's on a 13X7 with 4.5 backspace. No problems. I ran primarily at WillowSprings and Buttonwillow (So. Cal.) where track surface temps are usually 100-140+ from May-Oct, tire warming wasn't really an issue. 2-3 hard applications of the gas and brakes in the miidle of the warm up lap put enough heat for my confindence in turn 1/lap1. None of that zig-zag, pick up some marbles while you're at it, required.

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Daryl DeArman
I Love RX7's...they taste like chicken :P
 
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