Justarius

I recently bought new Goodyear Eagle F1 DS-G3 summer tires @ 245/40s to go on stock rims. About to have them mounted today and I figured I should do an alignment as well. Help! I did a search on settings and I'm totally overwhelmed and running out of time.

My car is totally stock and primarily used as a daily driver (mostly city but lots of back roads highway in the summer too). I'm fairly aggressive driver, hard on the corners, on-ramps, starts and stops, etc. I haven't done any racing yet but I plan on joining my local Sports Car Association this summer and doing a couple of track days (the kind with lots of cornering, no pure oval tracks) and maybe an autocross event. So maybe 2-4 racing days per year max? Have to see how it goes but 2 at least ideally.

Tire Rack says for assertive daily drivers ("driver who enjoys driving hard through the corners and expressway ramps") to go for max neg camber, max pos. caster and "preferred toe" (whatever preferred means) while staying within factory recommendations. For competition driving, they say also go for the "most aggressive toe settings available from the car and permitted by the competition rules". I assume I should stick with the assertive driver advice?

But I've read a whole whack of different stuff while searching the threads here and I think I'm out of my depth!

Some people say 2 or 3 tenths more neg. camber in back is ideal. Others argue the other way around. How about sitting in the car during alignment? I'm a pretty big guy (6'4", 280+ lbs, yes I fit just fine )... I will most likely have a passenger (140 - 180lbs) during the track days too...

And what about tread life? Daily driving is still my #1 use...

Anyway, I know these questions have been asked before but it's hard to get good general advice when everyone has a different setup and my alignment is this afternoon so not much time to sink my teeth into all this knowledge.

Hence some recommendations would be appreciated!

As always, thanks for your time

Justarius

costello

Since you're using it as a daily driver just go with max negative camber in the front and zero toe all around (maybe just a little bit of toe in for the rear). You can go a little more negative camber in the back relative to the front. I think you can get -1.4 degrees camber in the front stock so maybe -1.8 for the back.

Using zero toe will help the tires last longer since they'll be rolling parallel with the direction of travel. Giving toe out in the front helps the car turn into the corner a little bit better since they're already kinda pointed towards the turn, but the car can wander around on the highway.

You want slightly toe-in or zero toe in the rear for stability also. Toe out in the rear can make a car seem "loose" and want to swap ends. I don't know too many folks who run toe out in the rear for RWD cars. The RX-8 turns pretty good to me.

As your driving improves, you can also take out some camber in the back to also help the car rotate a little better.

Corentco

+1 on Costello's recommendations

This is the most streetable/aggressive setup I'd recommend for a daily driver. The rear toe if slightly inwards will offer stability and a more planted feel. Go slightly more negative on the rear camber but don't exceed the factory specs. -1.4 front and -1.6 to -1.8 on the rear would be a nice setup.

The car has a great setup from the factory and really is one of the best handling cars on the road.

Hope this helps.

lshu

I have the same tires as you (same size 245/40/R18) and run -1.0 front, -1.5 back, 0 toe and am very happy with it. I drive pretty aggressively and so far after 20,000 miles the wear is great and even! I still have many miles left on these tires even after 2 track days at Streets of Willow and Horse Thief Mile. They held up to heat very well and didn't get greasy until the end of each run. On top of that the tires are also very comfortable and quiet.

HOWEVER, to warn you, I was shocked at how soft the sidewalls felt on the GS-3Ds on the stock rims compared to the original Dunlops. While the tires are great on grip, it almost felt unsafe to drive aggressively from all the squirmy-ness of the tires, even when I upped the tire pressure to 36 psi. I ended up buying wider rims to better support the tire (Enkei RP-F1s 18x9.5) and this helped tremendously. It still feels a bit soft but at least much more controllable now when handling aggressively.

Justarius

Thanks guys, great responses, I followed your advice and I *think* I came out Ok.

The short of it was, the MAX factory recommendation would allow for front camber (or rather the minimum since we're talking negatives) was -0.9 on a 2005 RX-8 Sport Suspension. In practice they couldn't get more than about -0.7 (-0.6 left and -0.8 right). I asked why left and right weren't equal and was told it's impossible to get them 100% the same and that difference is "splitting hairs". Rear they were able to get -1.1 (-1.0L and -1.2R) kinda range. Which meets the goal of rear being more than the front at least.

Any ideas why my values are so much less than what people have been posting? -0.7 front is a ways off from -1.4! And so is -0.9 which he showed me on the screen is the MAX amount of neg. camber Mazda would allow for the front. It listed -1.9 for rear which sounds more like it but I couldn't have got the front to -1.4 without going outside the recommended range.

However with me sitting in it they said I added a full -0.5 to camber which comes closer to what you guys were thinking was a good target (something like -1.2F and -1.6R). I couldn't see the screen when I was sitting in the car so I had to take their word for it.

Come to think of it, wouldn't that extra -0.5 put the front outside of Mazda's -0.9 max spec for Front? I never thought to ask them that and at that point I think they just wanted me out of there. Also I-m guessing Mazda's specs are for an unloaded vehicle...

For toe, I got the front set to zero and rear was slightly in (1/32")

Caster didn't change, it was at 6.6L and 6.3R and stayed there. Max settings list 7.1 so it's still in the upper range which Tire Rack recommended. Since you guys didn't mention it I thought I should leave it alone.

Well that's about it. Hopefully I came out Ok. I didn't have 100% confidence in these guys because they kept asking me for settings and the 1 guy races cars so I felt he should have had his own ideas but what can ya do. I'm certainly glad I had your advice going in!

I'm just not sure why the specs were so far off from what I've seen people shoot for. Unless everyone is quoting "while sitting in it" stats?? Or ignoring factory recommendations?

Justarius

Thanks, good to know! Especially about tread life which is a concern. I already noticed the improved road manners. Can you give me an example of the "sqirmy-ness" you noted? I decided to take it easy on the tires for the 1st couple hundred miles cuz I read somewhere it's good to break them in but even still, on 1 corner I felt a little rear end wiggle and I wasn't taking it all that aggressive. Surprised me and I wondered about my new alignment... but I also figured the tires are brand spanking new. But maybe it's the sidewall/stock rim issue you noted? I talked to a few other guys with stocks and these tires and everyone seemed happy but I don't know if any of them had done any serious track driving.

p.s. -1.0 front camber was within Mazda's Min specs for you? As stated in my previous post the computer showed -0.9 min for a 2005 RX8 Sports Suspension (I had them check the normal suspension too which was the same)

imput1234

iTrader: (6)

Thats weird, the tires I run have no tread anyways lol so tread wear is not a concern with me. Right now I'm running -1.8 front, -2.0 rear.

Next time I get an alignment, I'm going -2.0 front, -max rear.

costello

Don't sweat it too much. Your numbers sound pretty good. Sometimes you just can't get more than -1 degree camber from the front of a stock car. Come to think about it, I think I was gettting -0.9 degrees max camber from the front when I had my stock suspension for the RX-8. For comparison, my 99 Miata has -0.9 degrees on the passenger side and only -0.7 degrees on the front driver side even with me sitting in it. It's my autocross car so I just left it at that and didn't try to even up the numbers.

Factory recommendations and what you can actually get from a car are 2 different things. A lot of shops who do alignments have no clue how various changes affect handling. They just punch in the vehicle make and model it spits out a range where they just try to have the alignment in the "green" zone. This is perfectly fine for a street driven car, but if you're trying to set up a car for competition then you can ignore the factory recommendations and go out of the spec ranges to get the car to provide the most grip and the handling characteristics that you want.

TeamRX8

iTrader: (25)

max caster is a general theory that doesn't apply to an RX-8, mine is below 4 deg

the factory specs are intended to make the car safe i.e. understeer

lshu

Yep, all new tires need a "break in" to wear off a protective coating on them, so they will be a little slippery for a while. You probably felt this just now (not related to alignment). The grip will improve gradually over the next 500 miles or so until the coating wears off.

Regarding the alignment specs, that's strange you couldn't get more than -0.7. As costello said it's probably just Mazda's min setting for an acceptable factory alignment for safety and non-excessive wear on tires (but not the greatest for performance). It was very easy for the people at my alignment place to get -1.0 out of the front suspension. They could have gone more negative if I wanted to (I watched them adjust the camber bolt and it still had some room to turn). They were using a new laser alignment system, and showed me the specs on the screen as they adjusted it in real time.

The squirmy-ness I'm trying to describe was from the kind of slow transitional responses as you flick the car quickly left or right. I just think that for this tire 245/40/R18 is too wide for the stock rim. As an example, there's a nice corner on my way home I like to take fast. Let's say I make a quick turn. The car first understeers because as the car leans the front tire sidewall is still flexing as it goes towards its most compressed state, so no grip yet. When the front tires "set", then front grip kicks in but now you start oversteering because the rear tires haven't "set" yet. When both ends set then it's all good. But it's this kind of behavior that discourages me from flicking the car like I could before with the Dunlops. It's just hard to tell exactly where the car is going. The tires seem to "average" your steering inputs to put you in the general direction you want to go.

On the track with my newly installed Enkeis, these tires had great stability on the low and mid-speed turns, but on the high-speed sweepers you start getting nervous. That's when steering inputs you make doesn't translate into turning the car until like .5 seconds later. Going at like 90mph, that's 66 feet your car isn't doing what you want! I had to compensate by making my steering adjustments early. Not the most confidence-inspiring qualities you want from your tires

Astral

I've ran with -1.8 camber for 4K miles and then -2.2 camber on the rear for 6K miles. I've experienced measurably (within 0.5/32nds) even tread wear on the rear. This was running with slight toe-in and then with 0 toe on the rear.

Whereas in the front, I ran similarly low -1.2 camber for 4K with even wear. However, at my 4K alignment (done 200 miles after lowering springs), the front springs must've settled or something, as I got pretty severe toe-out wear over the course of 5K miles or so (inside shoulder worn a lot).

I'm not saying that camber doesn't wear tires unevenly, but, in my experience, nowhere as severe as bad toe.

Could you please elaborate as to why? The factory manual specs 6+ deg on the caster, but I don't see how that could relate to understeer.