High speed cornering

IS300h · June 5, 2018

Hi everyone,

I've just put my first couple hundred miles on a new IS300h, but is it normal that this car feels as if it's all over the place when going through (motorway) bends at high speed?

Is it due to the extra weight in the boot? Before this car I've always had (rwd) BMWs, and never had any issues with high speed cornering.

At lower speeds (below 60mp/h) the suspension feels perfect and the car really sticks to the road, but from 70~80mp/h the car feels really "swirly" and the tiniest steering corrections (only in a bend) make you feel as if you're driving a boat. Braking at higher speeds in a corner is also definitely something you'd want to avoid (which was never a problem in any other rwd vehicle I've driven). If you do, it feels as if the boot wants to overtake the rest of the car...

Thanks for sharing your experience...

Carl1983 · June 5, 2018

Hi

which version of the IS do you have? I have the F sport with 18 inch alloys and the firmer suspension and don't experience the behaviour you are referring to.

cheers

IS300h · June 5, 2018

It's the CO2 friendly business edition which came with the smaller 16" wheels.

However, I put on 17" wheels myself immediately after taking delivery of the car as 17" was not a dealer possible option due to the CO2 emission and the conformity certificate for the business edition.

(In order to have 17" wheels I would have had to pay an additional 9k euro to upgrade to the Executive version...

So I have 225-45-17 both in the front and rear running at 2.5 bar (I believe 36psi) as mentioned in the owner's manual.

Of course I also had to transfer the TPMS sensors and afterwards I had to hold the TPMS reset button (hidden under the steering column) for 3 secs in order to clear the tyre pressure warning light.

I have new tyres in the rear, but the ones in the front only have about 5mm left (slightly more worn on the sides) as I bought a used set of wheels (OEM lexus though, in perfect condition).

Rear is Dunlop Sport Maxx RT2 (weight index 94)

Front is Dunlop SP Sport Maxx (weight index 91)

Could the tyres really have such a huge influence on the handling? It's a brand new car, only has 200miles on it now...

Tel · June 6, 2018

Zero cornering issues @ high speed in the Alps.

Your set-up is wrong or there is a fault.

Try another car.

Tel

ganzoom · June 6, 2018

Our 2015 IS300H handles much better than my old BMW 335i with stock M sport suspension and nearly as good as the 335i on bespoke Bird B3 suspension kit.

Push the car hard and the inheret behaviour is understeer not oversteer which your describing. Infact I've hard ever experienced anything remotely close to oversteer our IS.

ganzoom · June 6, 2018

5 hours ago, IS300h said:

I have new tyres in the rear, but the ones in the front only have about 5mm left (slightly more worn on the sides) as I bought a used set of wheels (OEM lexus though, in perfect condition).

Rear is Dunlop Sport Maxx RT2 (weight index 94)

Front is Dunlop SP Sport Maxx (weight index 91)

Could the tyres really have such a huge influence on the handling? It's a brand new car, only has 200miles on it now...

So your front tyres have little grip due to been used and rear tyres lots? - That may be a reason for the odd handling.

Rabbers · June 6, 2018

I can’t recall other reports of high-speed cornering instability over the years, and nor, as a former IS300h owner (though mine had the fatter rear tyres), did I ever experience the problem even when the tyres were coming up for replacement - and probably at speeds higher than you may customarily be aiming for in the U.K. Whatever the case, brand-new rears and relatively worn fronts may well represent a dodgy combination requiring expert advice.

IS300h · June 6, 2018

Thanks for everyone's feedback, much appreciated.

I'm starting to suspect it may be the (new) Dunlop RT2 tyres... After reading several reviews, I found that other people have similar problems with these tyres:

http://www.sciroccocentral.co.uk/forum/viewtopic.php?t=24059

Some of the comments are e.g.:

"I've had the Dunlop sport maxx rt 2 - for about 1 week, took them off.
They are a pretty soft tyre (although I had non XL version), and too soft a sidewall. Although were a very quiet and smooth tyre.
When pushing hard they frightened the **** out of me as the car suddenly snapped as I cornered fast and almost entered a spin.
They just did not inspire confidence when cornering hard, felt wallowy and not in control - and seem to suddenly fall off a cliff in an uncontrolled fashion rather than just gradual understeer."

...Which is pretty much what I'm experiencing. Feels indeed almost like driving hard on winter tyres with the softer compound...

Looks like I'm gonna have to replace the tyres.. Anyone have any suggestions on this? Good Year Eagle F1 Assymetric perhaps? (I've always had those on my BMWs).

If this would be really the case, then this would be unbelievable for an A brand like Dunlop, and why would they call it "sportmaxx"...

wharfhouse · June 6, 2018

I have standard suspension on my IS 300h (not F Sport) and 17" wheels with the OEM Yokohoma tyres and the car feels well planted around fast curves - came from a BMW 330i and the IS maybe a touch less nimble but no complaints or concerns like you are experiencing. At the moment my rears are due for replacement (just getting down to the tread wear indicators) and the fronts about half tread but other than if the road is slippery when the rear might feel a touch light still no issues. If it's a new car and you still have the 16" wheels and tyres then maybe worth putting them back on and seeing if that changes anything. Otherwise, unless there is a problem with the 17" rims you purchased sounds like the tyres.

Chris111 · June 6, 2018

11 hours ago, IS300h said:

I have new tyres in the rear, but the ones in the front only have about 5mm left (slightly more worn on the sides) as I bought a used set of wheels (OEM lexus though, in perfect condition).

Rear is Dunlop Sport Maxx RT2 (weight index 94)

Front is Dunlop SP Sport Maxx (weight index 91)

Could the tyres really have such a huge influence on the handling?

Yes they can have a huge influence on the handling and it sounds to me like your front tyres are shot. How old are the front tyres? You say they are more worn on the edges. This to me indicates that they have either previously been run at the wrong pressure or the wheel alignment was out and they may now be running unevenly on the road surface. Also, you are now running XL tyres on the rear and non XL on the front meaning the rear is a slightly harder tyre, although I don't know if this may or may not contribute to the problem. I agree with Phil above that if you still have the 16" wheels and tyres you put them back on and try them to see if there is any difference. Or, alternatively, swap the 17" ones around and try that. As you have fitted larger and wider wheels and tyres it might be worth getting the suspension geometry checked as it may be your cars' suspension was tuned differently for the original narrower 16" ones.

I would also say that I got the sportmaxx RT2 fitted all round 18 months ago and it is probably the best tyre I have run. I know my car is a GS but it is a more powerful and heavier car than your IS and I must say I do not recognize any of the criticism leveled in that one quote.

Hope you get it sorted.

P.s. Just for info Goodyear own Dunlop.

rayaans · June 6, 2018

5 hours ago, IS300h said:

Thanks for everyone's feedback, much appreciated.

I'm starting to suspect it may be the (new) Dunlop RT2 tyres... After reading several reviews, I found that other people have similar problems with these tyres:

http://www.sciroccocentral.co.uk/forum/viewtopic.php?t=24059

Some of the comments are e.g.:

"I've had the Dunlop sport maxx rt 2 - for about 1 week, took them off.
They are a pretty soft tyre (although I had non XL version), and too soft a sidewall. Although were a very quiet and smooth tyre.
When pushing hard they frightened the **** out of me as the car suddenly snapped as I cornered fast and almost entered a spin.
They just did not inspire confidence when cornering hard, felt wallowy and not in control - and seem to suddenly fall off a cliff in an uncontrolled fashion rather than just gradual understeer."

...Which is pretty much what I'm experiencing. Feels indeed almost like driving hard on winter tyres with the softer compound...

Looks like I'm gonna have to replace the tyres.. Anyone have any suggestions on this? Good Year Eagle F1 Assymetric perhaps? (I've always had those on my BMWs).

If this would be really the case, then this would be unbelievable for an A brand like Dunlop, and why would they call it "sportmaxx"...

The 16" wheel/tyre combination is designed for economy in mind, not performance so Im not surprised by the behaviour as the tyres are relatively narrow for quite a big car.

In 16" size the tyres are mainly touring tyres rather than performance ones as well, especially those that have a huge sidewall.

BigChange · June 6, 2018

I must say after many BMW 320 years I did at first feel uncomfortable with the IS300 cornering but now its fine. It did take a little while. Maybe in your case it is the tyres but it might just be having to get used to the car.

Rabbers · June 6, 2018

2 hours ago, Chris111 said:

...the Sportmaxx RT2...is probably the best tyre I have run...

My RC also came with OEM Sportmaxxes, and although I’m maybe not quite as enthusiastic about them as Chris, they are a good all-round performance tyre. My own preferred tyres for the IS300h in terms of grip and general handling were Pirelli PZeros, which I found marginally better than Michelin Pilots and far superior to Bridgestone Turanzas.

dutchie01 · June 6, 2018

my previous car was a bmw 3 series and in my opinion the is300h chassis is right up there. neutral balance and it can handle many more horses. in 3 years driving i never managed to slide or even drift through a corner as the grip is too much or the power too little.

anyway, as it is anew car my suggestion would be to go back to where you bought it and let them sort it out, something sounds wrong here.

Sandoli · June 6, 2018

Hi, and sorry for my average english. I had a similar issue on my own IS which I bought last year. The important thing is that it is a 2013 year model, which means it is one of the first model built.

I had to battle a bit with the dealer to make him accept fixing the issue. I had a one year warranty and I paid nothing. There was a recall on the first IS 2013 models, I may be able to find the recall ID...

Anyway, my car feels now like a normal car while it was more like you described prior to the fix. Like a boat at high speed.

It had nothing to do with the tires or with the Battery pack in the boot.

Found the Technical Service Bulletin :

Notchy steering feeling

CP-0044L-0314_IR

IS300h · June 6, 2018

Thanks again to all for your helpful suggestions.

I had a closer look at the compound of the tyres today and the sidewalls of RT2's in the rear have a really soft feel to them, much much softer than the sidewalls on the SP Sportmaxx in the front. (PSI is the same front & rear).

I'll take the car to a tyre specialist this weekend and get their opinion on this, I'm still really suspecting those soft RT2's, so most likely I'll be replacing those very soon and let you guys know.

Afterwards, I'll also replace the front tyres (if still needed) in order to pinpoint the rootcause. I really doubt it could be anything else as the car is brand new...

(I'm also doubting the problem will disappear if I would put the 16's back on as these have a 55 sidewall and are only 205 wide, and unfortunately the tyres are not mounted anymore as I was going to sell them separately...)

I also asked the Lexus dealer about mounting 245-45-17 in the rear, but they told me that by doing so I would get problems with the ABS system. (Anyone heard that one before? )

@ Chris111 : What tyre size did you have on your GS for the RT2's?

ColinBarber · June 6, 2018

1 hour ago, Sandoli said:

Hi, and sorry for my average english. I had a similar issue on my own IS which I bought last year. The important thing is that it is a 2013 year model, which means it is one of the first model built.

I had to battle a bit with the dealer to make him accept fixing the issue. I had a one year warranty and I paid nothing. There was a recall on the first IS 2013 models, I may be able to find the recall ID...

Anyway, my car feels now like a normal car while it was more like you described prior to the fix. Like a boat at high speed.

It had nothing to do with the tires or with the battery pack in the boot.

Found the Technical Service Bulletin :

Notchy steering feeling

CP-0044L-0314_IR

Not a recall, a TSB which will be fixed within warranty if the owner suffers from the issue. This is quite a specific problem where the steering wheel will almost seem to stick in the straight ahead position after a period of no movement and you need additional force to overcome it - only does it at higher speed.

Chris111 · June 7, 2018

12 hours ago, IS300h said:

Thanks again to all for your helpful suggestions.

I had a closer look at the compound of the tyres today and the sidewalls of RT2's in the rear have a really soft feel to them, much much softer than the sidewalls on the SP Sportmaxx in the front. (PSI is the same front & rear).

I'll take the car to a tyre specialist this weekend and get their opinion on this, I'm still really suspecting those soft RT2's, so most likely I'll be replacing those very soon and let you guys know.

Afterwards, I'll also replace the front tyres (if still needed) in order to pinpoint the rootcause. I really doubt it could be anything else as the car is brand new...

(I'm also doubting the problem will disappear if I would put the 16's back on as these have a 55 sidewall and are only 205 wide, and unfortunately the tyres are not mounted anymore as I was going to sell them separately...)

I also asked the Lexus dealer about mounting 245-45-17 in the rear, but they told me that by doing so I would get problems with the ABS system. (Anyone heard that one before?  )

@ Chris111 : What tyre size did you have on your GS for the RT2's?

Tyre size for my GS is 245/40 18 (standard for all Mk3 GS with 18" wheels) with a 93 load index (XL is 97) and I do not consider them to have a soft sidewall. I still say the problem is your front tyres. You say you really doubt it could be anything else as the car is brand new, well, that maybe the case, but you have second hand tyres on the front that by your own description are unevenly worn.

IS300h · June 20, 2018

Sorry to have kept you guys waiting, but I finally got around to replacing the rear tyres... Problem is now solved!

I'm now running on Bridgestone Potenza's (S001) which have pretty much the stiffest sidewall you can get (needless to say my tyre specialist wasn't a big fan of them..)

Of course road noise has slightly increased (compound is also a bit harder), but I'll take that any day over such kind of poor handling on the Dunlop RT2's..

I'm going to write a complaint mail to Dunlop as these tyres are a complete joke, really unbelievable! I'll attach some pictures below so you can see for yourself. They should not be called Sportmaxx as these tyres have nothing to do with performance whatsoever.

I kept my front tyres on the car just to make sure they were not the problem by the way.

@Chris111: Your sidewalls are a bit lower (40) and maybe the DOT is also a bit older which might affect the compound (?) Next time you replace your RT2's, let me know if you can also make the sidewalls look like mine in the below pictures when they're off the car. Somehow I doubt it though as you don't consider them to have a soft sidewall.

I have to say I still notice the extra weight in the boot of course which is inevitably affecting the handling, but with the Potenza's I can now at least keep the rear under control at 80+mp/h corners.

Linas.P · June 21, 2018

On 6/6/2018 at 9:55 PM, IS300h said:

Thanks again to all for your helpful suggestions.

I had a closer look at the compound of the tyres today and the sidewalls of RT2's in the rear have a really soft feel to them, much much softer than the sidewalls on the SP Sportmaxx in the front. (PSI is the same front & rear).

I have had Dunlop Sportmaxx RT most of the time on my car, in fact still have part worn set on my old 17" wheels after replacement for 18". And never had issue with them - if anything I would recommend them as quiet and fuel efficient tyres, with very good grip. Obviously, issue is that in UK we have outdated laws and legal limits is 70MPH... I do some aggressive cornering, but that would have been 40-70MPH, not over 70MPH. If I ever dare to go faster it is mostly straight line on the motorway... so might explain why never discovered any issues. Though thinking about it - I have maxed out car few times on autobahn ~135MPH sill never had any issues.

The air pressure in the rear should not be the same - I cannot say for sure what should it be on IS300h, but on most RWD cars it is few PSI higher e.g. IS250 are 35F and 38R... Even then I still run higher pressures on Sportmaxx RT as otherwise they tend to wear outside (as under-inflated) so for 17" I woudl run something like 38-40 and if I would be planning to do high speed European motorways maybe 40-42.

wharfhouse · June 21, 2018

9 minutes ago, Linas.P said:

I have had Dunlop Sportmaxx RT most of the time on my car, in fact still have part worn set on my old 17" wheels after replacement for 18". And never had issue with them - if anything I would recommend them as quiet and fuel efficient tyres, with very good grip. Obviously, issue is that in UK we have outdated laws and legal limits is 70MPH... I do some aggressive cornering, but that would have been 40-70MPH, not over 70MPH. If I ever dare to go faster it is mostly straight line on the motorway... so might explain why never discovered any issues. Though thinking about it - I have maxed out car few times on autobahn ~135MPH sill never had any issues.

The air pressure in the rear should not be the same - I cannot say for sure what should it be on IS300h, but on most RWD cars it is few PSI higher e.g. IS250 are 35F and 38R... Even then I still run higher pressures on Sportmaxx RT as otherwise they tend to wear outside (as under-inflated) so for 17" I woudl run something like 38-40 and if I would be planning to do high speed European motorways maybe 40-42.

IS 300h on 17" rims is same tyre pressure front and rear when normally laden at normal speeds (36psi) - always stuck to this and just replaced my rear tyres which had worn down to the tread wear indicators nice and evenly across the whole width of the tread. In the past my rwd cars did need slightly higher pressure in the rears and had a tendency to wear the inner edges more than the rest of tread so pleased to see the IS maxed the tyre life with nice even wear.

Linas.P · June 21, 2018

Yes.. I have forgotten IS300h runs square on 17" (IS250 is staggered even on 17" 225 vs 245). However, I believe IS300h F-Sport on 18" would still have higher pressure in the rear (again probably because of staggered wheels 8 vs 8.5 and tyres 225 vs. 255).

wharfhouse · June 21, 2018

2 minutes ago, Linas.P said:

Yes.. I have forgotten IS300h runs square on 17" (IS250 is staggered even on 17" 225 vs 245). However, I believe IS300h F-Sport on 18" would still have higher pressure in the rear (again probably because of staggered wheels 8 vs 8.5 and tyres 225 vs. 255).

Yes I would have thought higher pressure in rears for 18" staggered F Sport too

Linas.P · June 21, 2018

which then actually leads me to another point - so if Lexus has decided that for sportier feel you need to run 18" with staggered tires and higher pressure in the rear, it could be assumed car with 17" and 225's on rear running lower pressure would result in say... less engaging driving dynamics. My point - it is hardly an issue with the specific tyre - more with the fact that R17/225/45 tyres on the rear axle is sub-par option for high speed cornering.

wharfhouse · June 21, 2018

Not sure that is completely true - my BMW 330i - not a car you could say lacked driving dynamics - had the same 17" rims with 225/45 tyres all round (front and rear) although in that case a slightly higher tyre pressure at the rear which is common with RWD - not sure why the IS 300h has the same front/rear pressures as it's the first RWD car I have had with this - I wonder if the IS 200t has the same pressures all round? BMW had the option of larger and staggered rims/tyres of course by moving to 18" so it was a personal choice whether to go for the slightly more compliant 17" all round or the slightly less compliant but maybe slightly more better ultimate handling 18" staggered - similarly to what Lexus is offering between the F Sport (and Premier I believe) and the rest of the range (other than the basic 16" rims) for the IS? In every day driving unsticking either choice of rears, especially with all the electronic "aids", is pretty much impossible anyway...