Tyre mix between front and rear axles on 2018 SL500

[lolboy147]

Hi all, I need help - yet again..

I bought a 2018 SL500, with 16K miles on it, in July 2020. For obvious reasons I haven't been able to go too far in it since. It has bags of power and runs beautifully but it's very skittish. I'm an old git of 66 so well used to rear wheel drive but this car gives me no sense of security, even on a straight road. Put a little power down and the steering feels light and almost disconnected from the road. In short, it's no pleasure to drive.

Now my last car was a GAD tuned 350CDI which went very nicely and I had a similar problem when I put Bridgestone F1 asymmetrics on the rear mixed with the original Continentals on the front. After lots of good advice from here I replaced the Contis on the front with F1's and with all 4 tyres the same all was fine.

So, I'm thinking I might have the same, or similar, problem. I have Yokohama Advan Sport (MO) on the front, and Bridgestone Potenza (MO1) on the back. Both are Merc specced tyres so, given that there is approx equal wear front vs back, which ones do I change out for the other brand? It could get expensive if I go the wrong way...

Thanks in advance all, Laurie

 

[MBDevotee]

Always put new tyres on the back of a car so you have the best grip on the back (is always difficult when they are asymetric, and not always possible).

However, I would make sure that you either just change the back, or change all 4 - which would give you a free choice on tyre as well. Costly, but others here will recommend a great tyre for it, so wrong choice unlikely then.

And do what I do and put a full self seal in there when you get them fitted, then you don't need to worry about them getting punctures etc.

 

[malcolm E53 AMG]

Welcome to the world of electric steering you’ll get used to it but there is little road feedback from it and the car may also be equipped with runflats and their inclination to bounce around with no compliance on our third world roads which makes for a very unsettling drive. My 435i was thus equipped and changing the runflats to conventional MIchelin PS4 tyres improved the car and made it into something more akin to their marketing speel

 

[lolboy147]

Thanks for the replies. I think I'll need to change some tyres as I don't like the front/back mismatch. Also, having googled the MO ratings it seems that the MO (on the front tyres) is designed to give a luxurious "soft" ride whilst the MO1 (on the rear) is designed for high performance cars - another mismatch. Rapidly coming to the conclusion that 4 new tyres might be needed. Oh well, que sera and all that. Any recommendations on the best tyres to get?
Cheers, Laurie

 

[rorywquin]

Always put new tyres on the back of a car so you have the best grip on the back (is always difficult when they are asymetric, and not always possible).

However, I would make sure that you either just change the back, or change all 4 - which would give you a free choice on tyre as well. Costly, but others here will recommend a great tyre for it, so wrong choice unlikely then.

And do what I do and put a full self seal in there when you get them fitted, then you don't need to worry about them getting punctures etc.

Front and rear on a SL are different sizes .

 

[A.J.]

I would change all to a premium tyre, I personally don't like either Yokohama or Bridgestone, both don't have great reviews. Both rubbish tyres IMO. Others on here will disagree I am sure. I inherited Nexen on mine, MB fit from new and are a bit iffy to say the least. However I do only waft around so it doesn't bother me me hugely. I will change for a premium tyre when they are worn sufficiently. Personally I will probably go for Continentals

 

[rorywquin]

Thanks for the replies. I think I'll need to change some tyres as I don't like the front/back mismatch. Also, having googled the MO ratings it seems that the MO (on the front tyres) is designed to give a luxurious "soft" ride whilst the MO1 (on the rear) is designed for high performance cars - another mismatch. Rapidly coming to the conclusion that 4 new tyres might be needed. Oh well, que sera and all that. Any recommendations on the best tyres to get?
Cheers, Laurie

Question is, will changing one or the other all make a difference? Maybe drive the car a little more (carefully ) and wait until you are really used to the feel of the car?

I'm not going down the road of recommending one or another - some very strong views here but I'd deffo go for a premium brand.

SL500 is a little more inclined to understeer that some. What mode are you driving in? S+ makes the steering a lot more direct.

 

[MBDevotee]

Front and rear on a SL are different sizes .

I know, that's why I said hard on an asymetric set up.

 

[rorywquin]

I know, that's why I said hard on an asymetric set up.

Missed that - apologies...

 

[JBell]

Thanks for the replies. I think I'll need to change some tyres as I don't like the front/back mismatch. Also, having googled the MO ratings it seems that the MO (on the front tyres) is designed to give a luxurious "soft" ride whilst the MO1 (on the rear) is designed for high performance cars - another mismatch. Rapidly coming to the conclusion that 4 new tyres might be needed. Oh well, que sera and all that. Any recommendations on the best tyres to get?
Cheers, Laurie

You don't need to put MO tyres on the car, this will limit the choice you have.

Go Goodyear Eagle F1 Assy 5 or Dunlop SportMAXX RT2. A good midrange is the Falken Azenis FK510.

The Dunlop will be a more pliant ride and quieter but they wear faster.

Front options

Car Tyres - MPV Tyres - People Carrier Tyres - 19" R19" - 255/35/19, 255/35R19

www.camskill.co.uk

Rear options

Car Tyres - MPV Tyres - People Carrier Tyres - 19" R19" - 285/30/19, 285/30R19

www.camskill.co.uk

 

[Mr Greedy]

Go Goodyear Eagle F1 Assy 5 or Dunlop SportMAXX RT2.

The Dunlop will be a more pliant ride and quieter but they wear faster.

I agree with this from personal experience.


However, I find it very odd that pairs different tyres on different axles gives skittish, uncontrollable, and by the sound of it almost unsafe behaviour. I could understand a little unbalance, but skittish sounds worrying.

I'd also get someone who knows what their doing with a Hunter tracking system to check the alignment.

Unlikely with the age, but a rear shock that's leaked gives the same.

 

[JBell]

I'd also get someone who knows what their doing with a Hunter tracking system to check the alignment.

I would have full alignment done anyway

 

[lolboy147]

Thanks again for all the advice. I do intend to have a 4 wheel alignment check done before I splash out on new tyres. I usually drive in Comfort mode as most roads round here are pretty slow. I do flick it into Sport when the opportunity arises of course. I'm thinking tyres because of my experience with my last car - the front/back differing tyres gave me a huge handling issue which was resolved when all 4 tyres matched. I was astonished at the difference that having all 4 tyres the same made. So, in summary, it sounds like alignment and balancing check first, and test. If no better then new tyres all round.

 

[Mr Greedy]

One other thing on the Dunlop SportMaxx RT2. I found them very very progressive (if that is the right term?), which not being a gifted racing driver I really liked. Even if I've got the wrong adjective there, my experience was that as you lean on them more and more, you can feel them starting to let go and wriggle more and more, so it's easy to know where grip limits are regardless of road condition, because I found the grip feedback was great.

I'm sure they don't have the best out-and-out speed and handling performance, but I was very reassured by not having a tyre that hangs on, hangs on, hangs on and they suddenly lets go at the (much higher) limit. Sounds too much like brown trousers time to me.

Plus they were comfortable. And quite.
I thought sacrifice of mileage for all of the above was the right sacrifice for me.

 

[John Laidlaw]

Tyres are an immotive issue....
Nothing much wrong in what you have so it’s personal choice
Currently I’m running 20 in GY Assy 3 F1- brilliant , best ever I’d say
But I’ve also had Michelin, Pirelli etc at various times also been great,,,,if what you’ve got is working who cares??

 

[JBell]

Tyres are an immotive issue....

More of an Automotive issue John

 

[JBell]

Currently I’m running 20 in GY Assy 3 F1- brilliant , best ever I’d say

Now on the Assy 5 as well

 

[s5tuart]

One other thing on the Dunlop SportMaxx RT2. I found them very very progressive (if that is the right term?), which not being a gifted racing driver I really liked. Even if I've got the wrong adjective there, my experience was that as you lean on them more and more, you can feel them starting to let go and wriggle more and more, so it's easy to know where grip limits are regardless of road condition, because I found the grip feedback was great.

I'm sure they don't have the best out-and-out speed and handling performance, but I was very reassured by not having a tyre that hangs on, hangs on, hangs on and they suddenly lets go at the (much higher) limit. Sounds too much like brown trousers time to me.

Plus they were comfortable. And quite.
I thought sacrifice of mileage for all of the above was the right sacrifice for me.

Another vote for the Dunlop's here as recommended to me by @JBell
Nice compliant ride even on skinny profiles and far better than the Pirelli's they replaced in every way IMHO.
They give good feedback if you're cracking on a bit and even when driving like a loon the traction control light rarely comes on.
They don't come out top in the myriad of tests but they are always around the top 5 which suggests a good compromise for wet and dry.
ps. I don't work for Dunlop

 

[DSK]

From what you say, they are not tyres I'd personally have on that car myself, having experienced them and being in the trade and tested many. The Yoko's are over rated in my opinion and not in the upper tiers for grip.

Similar to the what people say about the Dunlop's, I run Goodyear Eagle Asym 5 and the Eagle has always been my personal default favourite due to its progressiveness, consistent performance from cold and when warm plus its the only one that performs strongly upto around 1.8mm of wear.

Michelin were hit and miss and the despite the Supra 285's on the rear and regularly seeing speeds in excess of 160mph, the Michelins hated heat cycles and as new looking Michelin Pilot Sports had to be regularly replaced. However, the new Michelin Pilot 4 raised the game by a serious tangible margin and is a great performer with the Goodyear Asym 5 running on par with it as it now has stiffer sidewalls. Pushed to the limit, the Michelin has factionally better outright grip in wet and is slightly more vague at dead centre but steers a bit sharper without being twitchy. The Goodyear Asym 5 (which I'm also running) is just smoother in transitions between grip/slip and steering. Again this difference is only noticeable when driving in manners that one should not on the public road.

 

[lolboy147]

Thanks all. If the problem persists past alignment and balancing checks I think the problem will be the mismatch of tyres between front & rear, not necessarily on the individual merits of the Yoko's or Bridgestones. I'll let you know how it pans out.