Best tyres for 3MPS's

[Jeev]

In the next month I'll be trying 245's all round, wil let you all know how it goes once I stuff them under the (rolled and flared) guards...

Cost much to get the guards done?

[TD]

Cost much to get the guards done?

I have some options, not yet done. Will strip off 235's and clean up the RX8 rims first (paint?), then get the guards rolled and flared prior to fitment.

Average price around town seems to be about $160 for all 4 corners to get it done right.

[03blk]

I have some options, not yet done. Will strip off 235's and clean up the RX8 rims first (paint?), then get the guards rolled and flared prior to fitment.

Average price around town seems to be about $160 for all 4 corners to get it done right.

Looking at doing the exact same with my RX8 rims TD. Sent you a PM about it.

[TD]

Looking at doing the exact same with my RX8 rims TD. Sent you a PM about it.

And replied.

Do you know that our track will increase to +35mm (legal increase in Qld is +26mm) so we will die in a hellish fire of unroadworthiness...gotta be better than the hellaflush craze though, I actually enjoy traction and a big footprint

[duglet]

And replied.

Do you know that our track will increase to +35mm (legal increase in Qld is +26mm) so we will die in a hellish fire of unroadworthiness...gotta be better than the hellaflush craze though, I actually enjoy traction and a big footprint

Im already in hell


Happy Motoring
duglet

Sent from my iPhone using Tapatalk and Vodafail 3G

[TD]

But not with your wheel track Duggy! All within legal limits for you broski

Im already in hell


Happy Motoring
duglet

Sent from my iPhone using Tapatalk and Vodafail 3G

[03blk]

After the speeding fine I got in the post today I think my Hell-reservation is confirmed... Their goes 6 points..

And replied.

Do you know that our track will increase to +35mm (legal increase in Qld is +26mm) so we will die in a hellish fire of unroadworthiness...gotta be better than the hellaflush craze though, I actually enjoy traction and a big footprint

We'll make up stickers; 'Sunk 'n Flush: cos Phat rubs both ways'!

I think I'll make this my new signature.

[Nexus]

Nah, surely 6 points is punishment enough.

After the speeding fine I got in the post today I think my Hell-reservation is confirmed... Their goes 6 points..




We'll make up stickers; 'Sunk 'n Flush: cos Phat rubs both ways'!

I think I'll make this my new signature.

@ stickers

---------- Post added at 01:20 PM ---------- Previous post was at 01:14 PM ----------

In the next month I'll be trying 245's all round, wil let you all know how it goes once I stuff them under the (rolled and flared) guards...

Lots of scrub on the front inside track @ +50 (inside sidewall sitting 12.5mm inboard of the steering axis.)
Any additional steering weight with the 235 on @ +50 RX-8 rims?
Be interesting to see how it wears.

---------- Post added at 01:24 PM ---------- Previous post was at 01:20 PM ----------

hellaflush craze

Good choice of words

[03blk]

RX8 rims on Gen 1 sit 11mm further inward: 15mm further outward:

Attachment 7923

I'm running std 215/45 (I know: stretched) and have noticed a slight increase in steering weight but in a positive way: steering is less spongey. More noticeable is that torque steer has been significantly reduced and comes on in a more predictable manner.
I imagine going 225/40 would further increase the weight a little and reduce the torque steer characteristics a little more, whilst the 40 profile would reduce sidewall flex (not that 215/45's have a chance to flex much on an 8 inch rim).

My plan was for 225 or 235 front and 245 on the rear only. As Nexus asked: I'm also interested in how 235/40's go on these rims.

[tigamica350]

I have Yokohama ADVAN Sports on mine and I am pretty impressed with the grip and wear so far. At $800 a set pretty good value as well.

[Nexus]

Thanks. I'm measuring @ the sidewalls outermost edga rather than the wheel lip.
215 --> 245 = 30mm = an additional 15mm either side of the tyre.
Accounting for the offset (52.5 --> 50), it moves 2.5mm outward
Making the inside sidewall move 12.5mm inward. Wheel width isn't part of the equation I'm using it just assumes you have an appropriate wheel to fit the tyre width.

215 on Rx-8 wheels (+50.0) your inside track moves outward 2.5mm
225 on OEM wheels (+52.5) your inside track moves inward 5mm
235 on RX-8 wheels (+50.0) your inside track moves inward 7.5mm
245 on RX-8 wheels (+50.0) your inside track moves inward 12.5mm

225 on OEM wheels added steering weight that I noticed as well, reduced torque steer but also reduced positive feedback a little.
So you can imagine that if you're noticing the effects with changes on 2.5 and 5mm, then 12.5mm should be very noticeable might even have some significant negatives.

RX8 rims on Gen 1 sit 11mm further inward: 15mm further outward:

Attachment 7923

I'm running std 215/45 (I know: stretched) and have noticed a slight increase in steering weight but in a positive way: steering is less spongey. More noticeable is that torque steer has been significantly reduced and comes on in a more predictable manner.
I imagine going 225/40 would further increase the weight a little and reduce the torque steer characteristics a little more, whilst the 40 profile would reduce sidewall flex (not that 215/45's have a chance to flex much on an 8 inch rim).

My plan was for 225 or 235 front and 245 on the rear only. As Nexus asked: I'm also interested in how 235/40's go on these rims.

215 on RX-8 rims should show slightly lower steering weight, but perhaps the wheel width sees a wider contact patch.

[03blk]

Cheers for that Nexus.

After reading your words it seems that 225/40 would give only a 2.5mm reduction in track with RX8 rims. This is the most popular tyre choice for RX8 rims on 3's in the States. It does however significantly reduce the rolling diameter on an MPS. however I think this is std fitment on a Gen 2 MPS; correct me if I'm wrong. Other than throwing the speedo out a little: are there any adverse affects to this choice?

I'm keen to go wider at the rear though: 235 or 245. Any comments as to the effects this has on handling dynamics in general? I know Col's car (245 rear) feels really sure footed, especially at speed with the wider rear fitment..

[Nexus]

The differential in overall diameter can be a problem for dynamic stability controls....I've heard for instance that an RX-8 with oversizes rear fitments develops >90Km/h cornering instability because the computer assumes set rolling diameter range and interprets the differing rotational speeds as slip. DSC then tries to "turn the car around"

215/45 -- 225/45 show similar differences in diameter - enough to induce instability if fitted Front:Rear. 225/40 to 235/40 to 245/40 prob not so much, but it's something to test for if you're trying out the fitments, because it's not something you'd want to catch you by surprise...

is col's the same offset all around - i.e. not staggered? It is permissible to have different offsets on front to rear axles. i.e. +48 front +50 rear. higher offsets might make oversteer more controllable while lower increase the limits towards snap oversteer. Very hard to make overall assessments on what to expect there. I'd go +48 front +50 or +52 rear to try it out.
I'd expect a bit more control, less twitchy by reducing rack where a vehicle might be prone to snap oversteer etc (i.e. very heavy rear swaybar)

I'm uncertain of the gen2 offset, It's either +50 or 52.5 I think the latter, only difference to gen1 being 7.5" wide.

drifted off topic a little - i wouldn't expect the DSC to like any more than a very small diameter change front:rear - 235/40 to 245/40 would prob have the smallest differential between diameter
245 rear I'd consider a staggered fitment.

Cheers for that Nexus.

After reading your words it seems that 225/40 would give only a 2.5mm reduction in track with RX8 rims. This is the most popular tyre choice for RX8 rims on 3's in the States. It does however significantly reduce the rolling diameter on an MPS. however I think this is std fitment on a Gen 2 MPS; correct me if I'm wrong. Other than throwing the speedo out a little: are there any adverse affects to this choice?

I'm keen to go wider at the rear though: 235 or 245. Any comments as to the effects this has on handling dynamics in general? I know Col's car (245 rear) feels really sure footed, especially at speed with the wider rear fitment..

[03blk]

Great info Nexus. This stuff is really useful info and I hope other members are enjoying our chat!

Col's Car carries 225/40 front and 245/35 rear. The reduced profile rear brings the change in rolling circumference down by half what it would be if he had 245/40 rear:

Attachment 7943

So it effectively gives the same change in rolling circ. as 225/40 front and 235/40 rear: 1.3% change. however the 245/35 are that amount smaller than the fronts whereas the 235/40's are that amount larger.

Col's car shares the same wheel size and offset f & r: 15x8 and 48 offset. And it works. The smaller diameter tyres allow for more drop and with coilovers, quality rubber and sway bars the handling is great.

I'm leaning towards Col's set up now and am considering getting Yokohama S Drives from Tire Rack in the US. I got emailed a quote for $850 delivered in these sizes (not far off half the Oz price).

[2000MNLESS]

Great info Nexus. This stuff is really useful info and I hope other members are enjoying our chat!

Col's Car carries 225/40 front and 245/35 rear. The reduced profile rear brings the change in rolling circumference down by half what it would be if he had 245/40 rear:

Attachment 7943

So it effectively gives the same change in rolling circ. as 225/40 front and 235/40 rear: 1.3% change. however the 245/35 are that amount smaller than the fronts whereas the 235/40's are that amount larger.

Col's car shares the same wheel size and offset f & r: 15x8 and 48 offset. And it works. The smaller diameter tyres allow for more drop and with coilovers, quality rubber and sway bars the handling is great.

I'm leaning towards Col's set up now and am considering getting Yokohama S Drives from Tire Rack in the US. I got emailed a quote for $850 delivered in these sizes (not far off half the Oz price).

Wouldn't having wider tyres on the rear of a FWD promote understeer though??

[Nexus]

Wouldn't having wider tyres on the rear of a FWD promote understeer though??

Not necessarily, wider tyres have narrower contact patch as a rule, linear vs lateral grip is different...that is what you'd expect at first though. Stiff rear suspension tuning and sway would overcome that tendency, I would expect, presuming it's there without.

If you tune it towards snap oversteer and then fit the wider tyres, and if you want to try it narrower rear track...oversteer should become more controlled, I think.

I suspect this is why the interest. It's really the sort of thing that needs solid testing and feedback, though.

The main caution I'd put out with the rear tyre fitment is that after changing the fronts a couple of times, the rears will be getting worn, and you put new front on that diameter difference could start to confuse the DSC.

225/45 and 245/40 are another alternative to 225/40,245/35

[03blk]

The main caution I'd put out with the rear tyre fitment is that after changing the fronts a couple of times, the rears will be getting worn, and you put new front on that diameter difference could start to confuse the DSC.

Taking this into account, perhaps a combo like 235/40 front and 245/40 rear would take advantage of this wearing issue; the 245's have 7mm more diameter than the 235, so as they wear and front tyres are replaced, the difference is reduced rather than increased. Or is it the sudden change in difference that could confuse the DSC?

[Nexus]

Taking this into account, perhaps a combo like 235/40 front and 245/40 rear would take advantage of this wearing issue; the 245's have 7mm more diameter than the 235, so as they wear and front tyres are replaced, the difference is reduced rather than increased. Or is it the sudden change in difference that could confuse the DSC?

I don't think it would be the sudden change of new tires as such, rather that the differential has grown larger than would be comfortable by fitting the new fronts. The alternative you suggest could have the same problem when the fronts wear as the rears will have little gone from them at the first replacement, so the differential potentially climbs beyond safe margins - we don't really know exactly what those margins are but I think it would be safe to assume that it's a percentage point further than the differentials you would normally see from wear alone.

One unknown is if there is a difference in DSC behaviour between smaller fronts to larger rears or vice versa. It would be really interesting to take a bunch or tyres to a skidpan and track and then push it until you can feel, qualify and quantify how it behaves with the different fitments.

I'd expect that smaller rears would be the more stable of the two, with the possible side-effect of delaying traction control interventions etc; to the effect of a more permissive calibration. But without testing it's educated guessing. As the only example is cols, he hasn't discovered any glaring stability issues, then I'd be comfortable expecting larger fronts to smaller rears working well with minimal diameter differences, but there is certainly a possibility that the other way around - oversize rears - could have radically different effects.

You might find DSC intervening prematurely (interpreting the rolling circumference differential as front wheelspin) and inappropriately. It's absolutely something that needs testing. The idea has my curiousity piqued.

[Reedy]

Just got my quote in from tirerack, $1100 for a set of ad08's delivered. Seems pretty good.

What does the average place charge for fitting/balancing?

[03blk]

Just got my quote in from tirerack, $1100 for a set of ad08's delivered. Seems pretty good.

What does the average place charge for fitting/balancing?

Fitting and balancing is usually about $20 a wheel from experience.

Reedy: What you need to be careful of is that anything purchased and imported over the $1000 point incurs a duty tax at Australian customs. So you want to pick a tyre selection that stays under that amount to be safe. I'm not sure how strict customs are on this or what amount exactly you're charged.

I got quotes $850 delivered for a set of Yokohama S Drives which is totally worth the savings on local prices and stayed below the $1000 threshold.