Westfield Miata forum

[turboeric]

While I'm awaiting my kit, I'm contemplating wheels. The aftermarket wheels on my donor are of dubious straightness and are, to but it charitably, hideous. So to help me in my contemplations, could you chime in with what you're using for wheels (diameter, width and offset, and tire size)? I'll have the standard width wings on the car, so if you're running the wider ones, that would be useful info too.

Thanks! Help me spend money!
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Happiness isn't around the corner. Happiness is the corner.

[Usher]

I have two sets of wheels for my Westfield. One set is 15"x7" BBS RG-F with 42mm offset and Hankook Ventus R-S2 in 195/50-15. The offset and width on these wheels are probably a little too big for the car. I had to bend the front fender supports back quite a bit to get them to fit. As a result, my fenders rub on the side of the body when the steering wheel is at full lock.



For autocross, I've got a set of Kosei K1 TS wheels (14"x6" 38mm offset) with 205/55-14 Hoosier A6 tires. The 38mm offset seems better for the car, but the Hoosiers are too wide for the front fenders. I also had some rubbing on one of the rear (standard width) fenders and had to trim back the lip about a quarter inch. The rubbing in the rear happened because I didn't get the alignment perfect when riveting on the main body piece. If the alignment was perfect, I think the tires would just barely clear on both sides without trimming the lip on the fender.

[turboeric]

Thanks for that. I have a set of 15x7 37 mm offset OZ Superleggeras with 205/50x15 tires for my Miata that I can test fit, as well as my 15x8 +36 offset 6ULs with 225/45x15 track tires that I'm very sure won't fit. I was hoping to stay with 15 x 7 and 205/50x15 tires for the widest tire selection, but your experience suggests that might be squeaky even at +37.
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Happiness isn't around the corner. Happiness is the corner.

[Joe Mac]

I've got a set of Dezent wheels, 15 x 6,5, 35 offset, with 195/50/15 Marangoni tyres. I haven't got any problem to fit under the front fenders, but at the rear, 7 inches or less offset will fill much better. I will perhaps use some spacers at the rear, but in my case, just for the look because I don't drive the car on tracks !
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http://mywestfield.skyrock.com

[Big Cheese Dog]

The 6UL 15x8s will fit the big rear wings with some grinding on the outer lips. They will NOT fit under the front fenders with 225 NT01s. Kazzera 15x7s with 205s fit under the fenders with judicious adjustment of the brackets and possibly a slight grinding on the out rear lips.

[turboeric]

That's pretty much what I gleaned from your build log. Those Kazeras are +35 offset aren't they? I'm hoping the 6ULs will fit with 205/50x15s as I expect the NT-01s will be toast by the time the Westie is done. I don't mind massaging the wings to get a fit.
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Happiness isn't around the corner. Happiness is the corner.

[keith]

The Kazeras are a +30 - but that's not really important. The front fender supports are easy to reshape. The hard limit is the 205 tires, and it's possible that stretching those over an 8" wheel will cause problems. We're going to have 7.5" wheels in the front of ours soon.
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Keith
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FM Westfield
My Seven

[turboeric]

I guess part of what I'm trying to get my head around is how much tire I will need. With my "full fat" 2345 lb turbo Miata, a 205 street tire is never quite enough. The 225/45x15 NT-01s are wonderful, but I've never tried an R compound in a 205 to know how much of the wonderfulness is the tire and how much is the width.

Obviously, the Westie won't need as much tire as the Miata, but I don't yet have a sense of how much less.
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Happiness isn't around the corner. Happiness is the corner.

[JohnCh]

Lots of threads about this on the WSCC boardroom. General consensus there is that you don’t need 205s in the rear until you hit the 200hp mark. Prior to that 185s are best and 185s are always best up front. Some folks who track their cars and who have gone from 185s to 205s up front report that the wider tires don’t get hot enough and consequently the wider tires actually increase understeer. The narrower front tires have the added advantage of slightly better feel. The folks on BlatChat (UK-based Caterham Club) seem to have the same feedback, however, I notice here in the States that a lot of se7en owners who track their cars run much wider tires all around. I'm not sure if that's because we have a tendency to believe bigger is better, or perhaps our weather results in much higher average track temps. I’ve never seen anyone back up any of the above with tire temps recorded during testing, so take the above with a large grain of salt.

Also, these recommendations assume 13” wheels, which folks on those forums consider the optimal choice for a se7en. Not sure that is an option for the Miata-based cars. Over the years I’ve run 185/60-14, 195/60-14, 195/55-14 and now 205/60-13 all around. When I switched from the 185/60 to 195/60 using the same tire (AO-32R) I did notice a slight reduction in steering feel, but not an increase in understeer – although to be fair the car wasn’t tracked, so I never got enough heat in the tires to compare that aspect. The 205/60-13 are definitely the best combo that I’ve used on my car, but the tires aren’t the same (R888) so not a truly fair comparison.

-John

[keith]

Our car is faster with 225s all around than it is with 205s - but then again, it's also fairly powerful. Bill can comment on the handling change, he's got far more seat time in the car than I do. We are going to be installing a staggered set of 205/50-15 and 225/45-15 tires shortly, mounted on 7.5" front and 8" rear wheels.

13" is certainly an option with the Miata-based folks. Caterhams seem to jump from 13" to 16" for available wheel size, wheras we tend to focus on the readily available 15" size. One big advantage of the Miata-based cars is the super-common 4x100 bolt pattern which gives us a wide variety of wheels from which to choose - not something you can say about the oddball bolt pattern used on other Westfields or Caterhams.
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Keith
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FM Westfield
My Seven

[turboeric]

Interesting information. I'd like to avoid staggers at the moment, as I'm using an ABS car as a donor and I'm trying to retain the ABS. My son, a mechanical engineer, has done a bunch of calculations based on online info on weight distribution and CG and figures the ABS computer should be happy enough to work properly. The 205/50 and 225/45x15 combo may be close enough to the same diameter - some experimentation may be necessary.

John, I notice you're running R compounds as street tires. (Very nice website, by the way. Nice car too.) How's the wear and do you find that they heat-cycle out on you?

If I ran R compounds on the street, I'd certainly have a much wider range of tire size choices. If I stick with max performance street tires (which was my first instinct), I'm really limited to 15 inch sizes, mostly 205/50. The initial configuration of the car will be a stock 99 Miata motor, so not the same amount of grunt as John's car or the FM car, but once SWMBO gets over the palpitations of the cost of building the car, that may change.
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Happiness isn't around the corner. Happiness is the corner.

[Usher]

[JohnCh]

[keith]

Just be warned that the R888 and RA1 are not suitable for sub-freezing temperatures. Toyo warns the tires can actually crack. I run the RA1 on my car and they last and last. I think Bill's been running RA1s, R888s and Nitto NT-01s. We have a lot of mounted wheel/tire combinations here at the shop

There's a big difference between the R compounds and the old T1-S, no question. And a 205/50-15 is close enough to a 225/45-15 that ABS should be okay.
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Keith
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FM Westfield
My Seven