Hey,

From the guide sticky above:

"On 7" wide wheels, offset can be anywhere from +40- +46, though +40 puts the wheel as far out as possible, and will probably look the best. (otter)"

OK, but on something like Kosei K1 TS

Size Selected: 17x7
Price: $199 (each)
Estimated Availability: In Stock
Recommended Tire Size: 205/45-17
Wheel Offset: +42mm
** Lightweight: 14.1 lbs. **

The stock offset is 42... so if I go to to a 17x7 wheel in place of the stockies, yeah +40 - +46 will fit, but what offset will maintain the suspension geometry properly? I don't want to bone the geometry up.

Also, I'm looking for spring to do wheels and tires for Autocross. I hear good things about Falken Azenis tires. Any other RA drivers out there doing Autocross? What's the hot ticket for the lightest weight and the most rubber on the road? Any suggestions for 17.7.5 wheels that are light and don't look like crap? (Graphite Grey Mettalic '05 RA)

 

Stock offset is 46, however, you'd be better off with a 42 offset, will give the car a slightly wider stance, and it won't affect your geometry, that's controlled by other things (tie rods, camber bolts, etc)

14 lbs for a 17" wheel is damn good.

 

Assuming that weight is correct, but it's off of Tire Rack so I have to assume it is. Even if it's 15 or so it's still damn light. Now they reccomend a 205 width tire, but that sounds wrong. My stockies are 16x6" and take a 205... they must mean 215. I want to slap as wide a piece of rubber on it as I can.

Love to hear from somebody running an RA in Solo II. Now if they ever sell Evo's in Canada I'll be able to take it to all those damned subies!

 

I have gotten into autocrossing pretty heavy this year.
I run Flik Hornets 17x7's with a 42 offset and 215/40/17 Toyo T1S's that I got from Edgeracing.com. They are listed at 17 lbs. I chose the T1S's because they were on special and Edge Racing would bundle them with those rims for about $725 shipped at the time. I chose 215/40/17's because they fit the rim, and they were very close to the stock size (for street driving and speedometer reading). See here: http://www.miata.net/garage/tirecalc.html

The Falken Azeni's RT615's are an excellent tire and a popular choice this year. Also a good choice is the Hankook Rs2's. Kumho also makes the MX, but I have heard they take longer to heat up and start to grip. I assume you are going to run in a street tire class, otherwise I would point you in the direction of Hoosier tires.

Are you planning on running in a stock class or something else?

 

This is a pretty fun autox car, but you should do something about the understeer unless you want to be pushing all day long. Tie bar helped me alot.

In Autox with stock suspension setup tire quality will help more than tire size (ground contact patch anyway). You want something with a very strong sidewall so it won't roll when cornering.

You can overinflate your tires alot with cheaper tires, but you just give up some traction to counter the rolling. I usually run around 35 to 37 psi (depending on outside temp), but last time only ran 32 all around b/c I forgot (not prepared for a 24hr autocross, but it was lot's of fun) and noticed some substantial wear due to tire roll.

You can run all the way to the max pressure rating (usually 44 psi on a street tire, check your sidewall) minus the heat you will gain in a lap (amounts to a couple of pounds or so, start at 40psi and check after a lap) I have bfgoodrich gforce sports, not the best but good for the price. I have been recommended the kdw2's from bfgoodrich by friends of mine.

 

Thanks for the replies!

I am running in a stock class yes. I'm in a local club in Ottawa, Canada, so it's not an SCCA class system. It's much simplified in comparison, just ABCD classes. (However we get 6-7 runs plus fun runs at an event, which rocks.) I think I can go with good street tires and some basic suspension mods without bumping up out of C class. No way can I run B class and play with the AWD guys, so I won't go crazy with the mods. This is also my daily driver, so I can't make it ride like a tank either. My RA is bone stock right now... well except for a mild tint job. Tires and wheels are my first mod for sure. The stock Goodyear RS-A all seasons totally blow. I don't want to go R compounds yet, so yep street tires. Thanks for the other suggestions that I can compare to the Falkens.

As for the understeer, yeah that will be my next thing to tackle after tires. I'm thinking my first thing to do should be rear sway. Does the tie bar help much? I have a good handle on what a bigger rear bar will do, but not so much with the tie bar.

Lephturn

 

My RA is a daily driver too....but I think it would be fun to drive a race car every day (maybe that's just me). The wife has an Outlander if I want a comfy ride.
Anyway...
1. Tires -- seriously look at the ones I suggested. All 3 are good tires. I normally run about 10psi higher when autocrossing than normal street driving.
2. Suspension -- Sway bar is a much bigger difference than the tie bar (I have both....just got the sway and perches from RRM ). Tie bar basically stiffens the lower control arms from flexing horizontally....thus making the rear end easier to pivot/kick out.

That should get you started with the understeer problem that the RA comes with.

 

my next purchase will be r compounds im probly going to find some stock rims or stay with 16" iv heard that edge racing has about the best prices on r's ,what a difference though no spining just grip and rip.

 

My concern over changing offset is that I don't want to increase the nasty things that a bigger scrub radius brings.



More scrub radius = more torque steer for one, and minimal torque steer is one of the really nice things about the RA. The Sentra Spec V for example is a torque steering POS in comparison. Sure, some of that's drivetrain, but some is suspension geometry. I guess the real question is, will 4mm make any appreciable difference in torque steer?

Lephturn

 

You could try a set of 4mm spacers to find out before you drop all the money on new wheels.

 

Based on the research I've done on wheels... maybe not. Everything I can get in 17 is going to be a 42 offset so far, so I guess it is what it is. Great suggestion though for a cheap way to test it.

I'd bet there are a ton of folks out there with 17's at 42 offset on an RA out there. So, did those of you with rims that size see any handling difference? Any noticeable increas in torque steer?

 

Torque steer with my 17's is negligible....you still get some but it's not bad at all. My rims are 42 offset, BTW.
Torque steer is the least of my worries when driving hard in a controlled environment.

 

I did one autocross this summer but plan on doing more. I've actually been thinking of getting 16x6.5 rota slipstreams with 40 offset (14lbs). This puts the inside of the wheel exactly where the stock one is, and you just get the extra 1/2 inch on the outside. All my mods have bettered my performance, I think 17's would only be for show. Any other autocrossers go with 16's?

 

Well there is some reason to go with 17's, and that's for stiffness. Both sidewall stiffness and suspension. Going with 17's and a lower profile essentially increases spring rate all the way around, and stiffens up the whole car. Stiffer means travel essentially, keeping the camber and bump steer from getting as crazy. It shouldn't be so stiff that I'd need different shocks though.

I guess it's just that the tires I have on my stock 16"s are crap (the Eagle RS-A's it came with) and roll over so badly. I suppose a good set of tires on 16's would do the job just as well.

See I was thinking of these:
Kosei K1 TS Silver
Size Selected: 17x7
Price: $199 (each)
Estimated Availability: In Stock
Recommended Tire Size: 205/45-17
Wheel Offset: +42mm
** Lightweight: 14.1 lbs. **

Additional Specs

Bolt Pattern: 5-114
Finish Warranty: 1 Year
Country of Origin: Japan
Construction Type: G. Cast/Shot Peened


They don't make those in 16's. And 14lbs for a 17" wheel is damn light. Now with a 7" wide wheel, maybe I could go up to 215's also. Either way, wheels that are 1/2 the weight of the stockies is amazing. Dropping the unspring weight by that much is all good in the handling department. Plus, they look cool.

 

I have 215's on my 17x7's. Advantage = slightly wider contact patch, lighter weight than stock rims. You can't fit 215's on 6.5 inch rims (at least it's not recommended).
I do have to run lower profile tires (40 vs. 50 stock), so the tire pressures I run in autocross are much higher. Lower profile tires do have stiffer sidewalls, so my ride on the street is a little rougher....but I don't really care (I'm not a pu$$ who needs a cadillac-soft ride) .

I did 3 autocrosses on stock rims and tires. You can do it with 16's no problem.....just get better tires. I have found however that the stock tire size is a little weird, and good autocross tires that size (205/50/16) are rather expensive.