RXP33D

I'm not too sure if its ok but i replaced the rears only with 245/40/18 GS-D3's

but left the fronts stock RE040, and now when cornering moderately, one of the rear

wheels will start braking (EBD?) which i think is part of the DSC. But compared

to the RE040 at all fours, the threshold of the DSC is so low that I'm getting

used to DSC kicking in at every roundabout at 40KM+.

It was my dealer that got these tyres also. Help please?

Gomez

It's not EBD mate.....purely DSC kicking in. What brand of tyres are they? Sounds like they're still a little greasy. New tyres are like that for a day or two. Check the pressures and see how they go over the next few days.

Diabolical RX8

I have 245/40/18's on the F&R. I didnt feel a difference or notice a difference with DSC on. Just alot more grip.

If your dealer installed them like you said. Get one of the Serive Technicians to take a ride/drive in your car. Let them see it for themselves with you in the car so they know exactly what you are talking about.

Keep in mind that your dealership is supposed to provide you with parts that should fit properly on your car. So if they did it themselves then they should fix it for free.

RXP33D

They're Goodyear Eagle F1 GS-D3's.

A couple of places has recommended me driving constantly at 40psi. And that's what I've been doing.

It seems to be getting a little bit bitter as in the threshold is getting bigger. HAve been

driving with dsc off and the thing feels like day 1. I can't give any reviews as I couldn't even

drive when i bought the rx8 with RE040s on them.

I;ve seen alot of people with staggered rims not having any problems at all. I'm using stock!

Thanks alot though guys. Will let you know how things go.

mlx8

You have slightly, say by @ 3% different diameter tires front and rear. This may be enough of a roilling diameter difference to confuse the DSC. I don't know if the DSC is "smart" enough to re-learn, or teach itself to accomodate a difference in diameter, but it sounds like it thinks one end, i.e. the *** in this case, is "traveling" faster that the other and trying to recover you out of the oversteer spin that you are not experiencing :-)

pcimino

That's an interesting idea. In which case the tires should be rotated.

beachdog

That would just change the dynamics to understeer error condition.

RXP33D

I figured...

Haven't actually seen a car with wider tyres up front...

The problem seems to get better over time. Maybe its wearing in?

Yesterday's haeavy rain allowed me to test wet weather grip.

They stick even on hard acceleration on tight bends!

RXP33D

When servicing my car with tyre change couple of weeks back, he told me this had happened to another guy aswell. I'm still getting this problem. The man that told me that is on holidays unfortunately. But another salesman i talked to told me its because of my staggered tyres.

Then I said fair enough, but i ain't spending $950 on a pair when theres so much tread left. Also, how many bloody people have staggered rims and tyres on this forum with NO problems! Perhaps the wheel speed sensor or somethings been screwed about during tyre change?

bxb40

You are mislead in terms of what pressure to use. I go usually 34PSI in rear - on rare occasions 36PSI. I can feel what you describe more and more if pressure increases from 32 to 34 to 36. I don't even want to try 40PSI as the car will lose the end traction most of the time. So, drop the pressure to 34PSI and see if you have issues. Also, tires wear at 40PSI will not be uniform. I run all seasons 245/40R18 all around and the rear needs about 2PSI less pressure than the front to have equal tire wall flex (turning response) and all around traction (front grip in fast turns and rear traction).
As for staggered setups: the diameter of the tire is very close, just the width are different, so no reason to "confuse" the DSC.

RXP33D

Thanks for that bxb.

Will give it a try.

But as I'm running gs-d3 rear and re040 front, the rear feels bouncier than usual on turns,
assuming its because of the softer sidewall?

yiksing

Please use same tires for all, not just DSC will get confused, ABS will too.

RXP33D

But then again viksing, what about others who are using staggered setup?

I don't know of anyone with DSC problems who have rims(staggered).

beachdog

It's all a matter of how closely matched the circumferences of the different sized tires are. The systems depend on measuring and comparing the rate of rotation of the wheels. ie both rear wheels rotating faster than fronts = error condition or left wheels rotating faster than right for the specific amount of steering angle = error condition. If the sizes are different enough to cause a permanent difference in measured rotation you're going to have problems.

Gord96BRG

I know of at least one guy who had DSC problems caused by aftermarket rims/tires. He didn't like that answer, though.

There's a thread in the Tires and Wheels section about the implications of staggered setups; worthwhile reading.

yiksing

I'm not qualified to comment on this, the only thing my research yield is a more than 3% difference in tires circumference will cause the ABS to go nuts because the sensors are reading different speeds in front and rear tires. The DSC I guess would also be reading false speed so it would be trying to correct skid when they are not happening.

takahashi

haha... you really think that DSC is that accurate.

I am with Gomez, the tyres are green. It should settle down in a 1000km or so.

Tyre pressure and 3% is minimal in street driving. There may be more to feel if you are doing a 130kmh corner on the race track.