takahashi

Guys, could there be a chance that a 225 on one tyre will fit the 8" better than another tyre? I am start thinking that....

But I also hear the comment that the stock 225 was a very tight fit for the stock rim and it is easier to fit a 235 and a 245 in the stock rim...

I think the 245/40 is the best match for the 225 in terms of circum but I think 235 for road use is great there is only 1kmh difference when Stu and I are playing with our cruise control on Hume. It is the best feeling I get for steering IMO (love my Michellin )

Keep gathering thoughts on difference size since Nankang may be able to produce a 235/40

For the tyre pressure - I think during the Nats we have a quite warm track and a few of us are dropping tyre pressure to reduce bounce - I come from 36 cold (that is why I came in early after the first session guys) to 29 psi cold on my semis and still think I am overpumped. I think people have it 32 psi cold for the track and worked well.

timbo

Yes, I usually run about 38psi for that very reason. But after running them on the track you can still feel them moving much more than I recall for the OEMs. This was proven objectively by MACCAA and cronullarx8, too.

I guess Mazda settled on the 225 size for a reason. It's just a pity they haven't lobbied more tyre mfrs to build them

MACCAA

I think it's more tread design than the 245 width that is the problem.The Toyo T1R's that I use and the YOKO's Timbo have are a similar tread,much like a wet weather race tyre design.It's the tread that's moving,not the tyre being overwide for the rim.Rod's 245 Bridgestone SO3's are more like the OE tyre in tread,and were better.
Having said that,the Toyo is a better road tyre,quieter and better riding.Depends what you are looking for in a tyre.
Now if they made the OE tyre in 245..........
Cheers
Len

takahashi

Coz 225 is a common size in Japan and 235 is a common size in Europe - do I sense this right? I conclude this since I read a lot of ads from tyre shop in japan and 225 dominates the on sale new tyre section. Most car now are in 225 (some are 18" but most are 17").

RXP33D

I'm running 245/40/18 rear (eagle F1 GSD3);
225/45/18 front (RE040);

And the setup is completely messed up for me. DSC intervention threshold has dropped to a ridiculous point that I'm scared to take a rounabout at the speed limit!

Either my DSC is screwed or what others have been saying is that the car is reading different speeds on the front tyres and rear tyres hence slipping and the DSC kicking in. With the DSC OFF the grip is amazing even on my shoddy front RE040s worn out. I don't think I've had any tyre squirm since a couple of months back with RE040s all around. I like the staggered setup, besides the DSC problem that comes with it, but have a good feeling that 245's all around won't be as exceptional.

Is this DSC problem occurring with your setup wildcard?

labrat

When yuo think about it, thi and other similar threads started because Bridgestone service the Australian market so badly. If as Taka says, the 225/45 is such a common size in Japan, maybe we should be writing to various tyre companies alerting them to the fact that the supplier of stock tyres to the RX-8 has essentially abandoned this car in Australia. Given that these are high margin tyres, we may attract some other makers to providing some competition. When I wrote to Fulda mentioning the performance of the 245/40's, I told them that Bridgestone wasn't doing much of a job here for us and they could possibly have a piece of the action if they made 225/45's.

timbo

Just a thought. Try resetting the ECU. Maybe the DSC will recalibrate itself to the new sizes after the reset. The sizes aren't that different and there must be plenty of people now with staggered set-ups

RXP33D

Good point Timbo. Have had a thought about doing this, but don't know how to reset the ECU?? LOL

Search is my best friend i guess...

EDIT: Have done the brake pump and ODO RESET 'TEST' thing and its still a problem.

How do I get the fronts to wear out quicker so I can go 245 all around? LOL

Wildcard

I can't say I have noticed any DSC problems with the new tyres.

It's hard to say though, because with the supercharger I am seeing more DSC than I used to anyway.

sco

The tyre size is a parameter that is configured in the PCM... AFAIK it isn't "learnt". The latest flash (recall) apparently increases the threshold for the DSC kicking in. I'm yet to confirm... need to take the car to a few places where I could reliably get it to kick in (due to rough road conditions around a corner).

It is annoying that these updates get installed with no owner information provided... changing this sort of stuff can be a safety issue. "Release notes" or manual addendums should be provided to owners particularly when the changes are significant.

RXP33D

I've only noticed a threshold decrease in the DSC system since my new flash.

staggered 225 245 isn't the way to go for my car it seems.

EZZY

get it check out again tuan, i have had no problems with my 245/35 and 275/30 staggered setup

japfan

Have now done 10000km's on the Nankangs. Everything appears to be OK. Driving experience has not been diminished for road work.
Am starting to get a noise like a flat spot though at above 100kph so i will reserve my opinion for another 5000km.

Wildcard

I am not experiencing any DSC problems with the staggered 225/245 setup. I wouldn't expect it to either. The rolling diameters are almost the same.

auzoom

If you aren't aware I smashed my rim a while back and thoght the tyre was OK. Well turns out the tyre WALL was OK but the tread surface as a buldge. As well I need to replace the wheel hub(?).

Anyways, I have been quoted ~$420 (give or take $10) for a single Potenza RE040 and also sourced Nankang 235/40ZR18 XL 95W for $145 a tyre.

Does anyone see an issue with running the 235/40 Nankangs at the rear and 225/45 Potenzas at the front? If not, then I will rotate the rears to the front and replace the rears with the nankangs.

Cheers

Andrew

RXP33D

I do.

I've had regretful moments. with staggered but stunned that wildcard is running with it fine.
I also made the decision to run two separate brands of tyres like what you're deciding now.
I'm thinking it could be the tread design thats causing dsc to go nuts. So my suggestion is if you go staggered, go staggered with the same FRONT and REAR. But as wildcard is using, staggered 225 245 in the same brand works fine for him.

auzoom

Are you saying go with the same "tread pattern" FRONT and REAR but different width?

Andrew

Hymee

iTrader: (1)

Cheers,
Hymee.

takahashi

Me too?

EZZY

i think thats what he meant.

and i dont think different thread pattern front and back would make the DSC go bananas.....

auzoom

Logically speaking I can see it being a possibility as different tread patterns and compounds will cause different grip conditions, therefore causing slightly different roationaly speeds being picked up by the DSC.

This of course is if rotation speed is what DSC uses to determine if the wheel(s) are spinning.

Andrew

Hymee

iTrader: (1)

I can not see different tread patterns causing more differential than as occurs normally, such as when you are driving around a corner, as each of the 4 wheels describes a different radius, hence rotational speed.

I can only believe one might have a "problem" if you used grossly different rolling diameters.

Cheers,
Hymee.

auzoom

Fair point, and also weights into the point that a few poeple are running 225/45 front and 235/40 or even 245/40 rears with no probs.

I just wonder how many who are having the problems are yet to get the new Flash that increases the DSC threashold and how many who dont have the problem do have it.

Andrew

RXP33D

Here's the scenario:
225/45/18 FRONT RE040
245/40/18 REAR EAGLE F1
DSC went skitz at Hyundai speeds on a bend or even a roundabout. (DSC THRESHOLD DROP)
All 4's 245/40/18 EAGLE F1. Back to normal.
Wildcard:
225/45/18 NANKANG
245/40/18 NANKANG
He says it works fine.

auzoom

Yep thats wht I thought...something like that anyway. Well at least at $145 for the 235/40's its only $290 to change over the fronts if its an issue.

Andrew