15X8 rims

[Maniac Mitch]

I didn't know where to put this question...but know this section gets a LOT of traffic.

Does anyone with a 1st gen Miata 90-97 use the TRM 15X8 C1 rims with the 225/40-15 tires? Tire rack's web site lists it with +20mm offset and 5.31" backspacing (15.0lbs ea). I see the 949 6UL has a +36mm offset...so I'm confused about fitment. I have coil-overs so *IF* my old brain still works right, these TRM rims are more inboard than the 6UL.

Who's the rim techie?

Anyone got a set of these rims on their 1st gen car with those huge tires?? Anyone got a lighter set for sale?

Thanks,
Maniac Mitch

[OZMDD]

+20mm will be less inboard than a same-width wheel with a +36mm offset. The greater the number, the more "tucked" under the car they become.

[POS Racing]

Good stuff here -> http://www.tirerack.com/wheels/tech/...jsp?techid=101

[Maniac Mitch]

Good stuff here -> http://www.tirerack.com/wheels/tech/...jsp?techid=101

I read that...but found it somewhat confusing...I rely on backspacing to understand it all. the 949 6UL website does not give a backspacing. However, I just reread the TRM C1M (miata specific I assume) that is only 15X7. It has +30mm offset and 5.19" backspace. So the C1 rim at 1" wider and only .12" more backspacing is shoving .88" outboard. Crap.

[driftdevil]

ImageUploadedByTapatalk1334794286.081090.jpgImageUploadedByTapatalk1334794361.748671.jpg

First pic 15x8 +20 with 205s and very low

Second pic 15x8 +25 with 225s and still very low

[Davidss]

I have a pair of 15x8 6ULs. They are not for sale but you could put them on and drive around the block to test fitment. In addition I have a variety of spacers to test other offsets.

I am in North Fort Worth near 35/820.

[FowlerMotorsports]

What's the best combo to use without having to flare the fenders out? (wheel offset and tire size) I am looking at adding some 15x8's here soon

[driftdevil]

Depends. Do you want to roll and maybe pull the fenders some? Are you looking to fill out the wells? If your wanting to fill the wheel wells and get some good rubber a 15x8 +25 with 225/45/15 RS3s are about the max as going with the +20 offsets will have you pulling the fenders quite a bit.

[Maniac Mitch]

Thank for the pics and info, Driftdevil. very informative info on tire sizes. I will be PM ing you shortly for more info.

To others, let me give some logic that got me looking at the TRM wheels based on BACKSPACE...which is old school and what I'm used to.
Goodwin Racing Website says to use 40mm offset. I converted that to 1.57". My current Rota Circuit 8 15X6.5" seem to adhere to that...taking the centerline at 3.25" backspace and add 1.57 I got 4.82" backspace which is reeeeeeeally close to what I measure.
Taking the TRM 15X8 wheel centerline with 4" backspace and add in that 40mm (1.57") recommended offset, I get 5.57" backspace. The Tirerack site shows that C1 rim to have 5.31" backspace...so it is .2" set farther out than optinum according to my research. So it was being considered. The weight is bugging the heck out of me, so I will to think on that. Goodwin's site says a max of 15lbs AND says several times that the factory weights are often advertised lower than what they really are. I trust Brian...he is a Miata guy and I've talked on the phone to him a billion times over the last 11 years....and purchased some items from him.

Maniac Mitch

[nealb]

http://www.1010tires.com/WheelOffsetCalculator.asp

[pyro4826]

Naturally RPF1's would be lighter, but good luck trying to find any at the moment. Most people I have talked to don't want to sell them.

[Sharpie]

Jamie the new wheels look friggin' awesome.

[driftdevil]

Thanks. I'm starting to like them even more. Mitch- no prob. I've probably done more research on fitting wheels on a miata than most even want to know so it's nice to be able to use it to help someone. Oh and by the way, the flatouts are only like 11-12 lbs and even with 225s they feel lighter than the trm with 205s. And they are pretty cheap. I got mine through Goodwin.