SimianSpeedster

I've been enjoying my car for just over 3,000 miles, but the ride quality on some of the roads I drive during my daily commute around L.A. has sometimes been punishing, and a few of the potholes I've struck have made me worry for my wheels and tires. I bottomed out the right front wheel on a pothole this week, and even at a moderate speed, the impact was quite harsh. On smoother roads, the ride quality is very good considering the handling prowess of the car, but unfortunately I spend decent amount of time on crap roads, and they're not getting any better.

As previously confirmed by others on the forum (thanks again), the stock 19" TTS wheels weigh 27 lbs. and the OEM Bridgestones weigh 26 lbs, and 53 lbs./corner on 35 aspect tires isn't a recipe for good ride quality on rough roads. I'm strongly considering switching to lighter (but hopefully equally strong) flow formed wheels and better tires -- Michelin Pilot Super Sports are my tried and true standard -- and I'm also thinking of taking the logical step of downsizing to 18 x 8.5" wheels to add some sidewall height to help with the impact harshness. I like the look of 19" wheels, but I have to be realistic as this is my daily driver and the roads here are savagely bad in some places.

I previously exchanged some back and forth with Jeffc and others in on one of my earlier threads, and he noted that the ride quality and noise improved on his TTS even when he switched to 27 lb. 18 x 8.5" winter wheels, and that the handling still seemed solid albeit during winter weather. Given that I would go with lighter year-round wheels (likely VMRs at around 21 lbs.), I'd expect an even bigger improvement in wheel control, and I expect the Michelins to be a better all around tire than the OEM Bridgestones while also weighing ~2.5 lbs. less each. I know no one on the forum can predict the outcome of my proposed change with certainty, but I think it's fair to assume that dropping 8-9 bs. per corner and switching to 40 aspect Michelin tires will make a significant difference in ride quality without sacrificing much in the way of handling.

Any additional thoughts/input/advice from the group?

Also, can anyone who has a TT with stock 18" wheels and drives on bad roads speak to their experience so far? I know the TTS suspension is a bit different, but any experiential info is helpful.

Thanks in advance!

Glisse

I think lighter wheels and Michelin Pilot SS tyres will improve handling and steering factors, but not significantly improve ride quality on rough roads. Specifically bottoming out on potholes. Increased sidewall height will reduce some initial sharpness and make the general ride more comfortable, but not the crash/bang of hitting the bump stops. That's all about suspension travel, spring rates, is it not? For potholes, a suspension that is too soft on compression can be worse than a stiffer suspension.

I have Michelin Pilot Super Sports on my S5, and they are excellent tyres. Whilst they ride a little better than the Pirelli P-Zeros that were OEM, I would not say they are plush. As a massive generalisation, I would say Continental has the best ride quality amongst premium high performance tyres. But your tyre thoughts seem to be almost at odds with your crap road issue? Is this man maths at work, LOL!

Audi do continue to sprinkle their catalogues with forged wheel options which are comparative bargains vs the cast wheels. As long as you like the design, of course. Funnily enough, the base 17" wheel on the base TT (which may not even be in NA for all I know) is a forged alloy wheel. I'm sure Audi doesn't really want anyone to buy it, but as the base model is used for compliance testing, you can see what they are doing there

The lightest wheel I have seen for a TT (have been looking for an RS3 wheel option) is from ABT in Germany. Their forged ER-F 19" wheel weighs 17lbs. Not that I am recommending it, as crashing into potholes is not the right application, and it is extremely expensive. Also, the weight saving of forged wheels (an to a lesser extent flow-formed wheels) is achieved by matching the equivalent strength rating of a cast wheel. You need a strong wheel, and maybe one with evenly spaced rim support? You could spend a fair bit of money, and not get much improvement

Jeffc

I switched from the stock 19" fare to the TT 18" wheels and the 15000 miles-old Pirelli P Zero Nero A/S tires off my trade-in S4. That made a noticeable difference. I would highly recommend doing it, but my TTS is still uncomfortable over tar strips, broken pavement, RR tracks, etc. If you really want a significant improvement I don't think the Pilot SS Max Performance tires are going to help. You should probably look at a softer all-season tire. Good luck.

n828cl

I put 19" Conti DWS 06s on my TTS in December, and the ride here on Minnesota roads is firm but acceptable, with pressures at 37 psi front, 34 rear. Noticeably better than on my Mk1 TT with 18" DWS 06s.

- Chuck

adg44

OK, first, what tire pressures are you running? This is one of the most important factors.

Are you in Individual mode in Drive Select and the suspension on comfort?

Going from a 19" tire to a different 19" tire and a lighter wheel is likely not going to affect your ride comfort. Yes, if you go down to an 18" tire which has a higher profile, it will add to ride comfort. But you also have to take into account what tire, load rating, extra load, etc, and even then it is hard to determine how a specific tire will feel.

We should not forget that this is a sports car and as such you will have a firm ride. The range of the magnetic ride should help with that, however.

SimianSpeedster

Thanks for all the feedback. Some responses to the group and a more thorough explanation of my thought process:

I have the OEM Bridgestones, I'm running 35 PSI front/32 PSI rear, and I usually have the suspension setting on Comfort in in my Individual profile when driving rougher roads.

My observations are interesting: when the suspension is set to Comfort, the wheels are unsurprisingly allowed a greater range of motion because the shock valving is effectively softer. On one hand, Comfort mode softens the direct impact of sharp wheel movements by allowing the wheels more freedom, but on the other hand, the reduced wheel control allows the secondary impact to be more exaggerated as the movement of all that mass transmits to the chassis. In fact I often find that changing the suspension mode to Dynamic has benefits even on medium-rough roads (let's say expansion strips and uneven pavement, but no potholes, etc.) because, while some of the individual impacts are a bit sharper, the overall impact to the stability of the car is minimized as the wheel motions are kept in better check. I haven't been bold enough to try Dynamic mode on truly rough roads yet, but perhaps I need to as a data point.

The underlying sensation is that the heavy wheel/tire combo on my car is taxing the dampers, especially in Comfort mode. The wheel movements feel exaggerated and less well controlled than hoped which is exactly what I felt on my 128i before I switched to lighter wheels and a stiffer suspension. Even with a much more aggressive compound and shorter sidewalls (I switched from 50-series Goodyear Eagle GS-As to 40-series Michelin PSSes) the ride quality on the 128i is quite good, and the reputable tuning shop I worked with mostly attributed it to dropping over 8 lbs. per corner in each corner while increasing the control of the wheel travel by way of the suspension change.

My biggest concern isn't bottoming out on a regular basis as I realize that's going to happen when it happens (hopefully not frequently). Rather, my primary goals are:

1) To afford the suspension a better opportunity to maintain better wheel/tire control, and
2) To reduce impact harshness when I do hit unavoidable road imperfections.

As I see it, #1 is best served by reducing unsprung weight, and I figure I can safely knock out 8-9 lbs per corner by going with high-quality flow formed wheels that should be as strong as the stock cast wheels (thinking VMR V810s). I'm optimistic that the lighter wheel/tire combo will tax the suspension less and result in less exaggerated wheel movements, maybe to the point where I can use Dynamic mode more often to further reduce wheel travel, which is effectively the same thing as stiffening the dampers.

As for #2, I am open to tire suggestions, but I've had 2 sets of Michelin Pilot Super Sports, and I've found that they are quite compliant given their incredible all-around capabilities. Most other reviews have found the same, though they do get harder as you approach the last 1/3 to 1/4 of their usable life -- the same can be said for many tires. The PSS ratings for ride quality and road noise on Tire Rack are consistently better than any similar performance tire, and they meet, if not exceed, the ratings of less aggressive all-season performance tires (they're effectively the same as the Conti DW 06s, for example). I can't imagine that the PSSes wouldn't represent an improvement over the stock Bridgestones, especially in a reduced wheel diameter (245/40-18s in place of 245/35-19s). As I see it, it's all relative. Still, if you have other tire suggestions, bring 'em on.

So, I'm awaiting an updated weight spec from VMR, but I think the 18x8.5" V810s will come in around 20 lbs (the 19x8.5" variant is 21.8 lbs.) Provided that's correct, I can drop 9 lbs/corner by switching wheels and tires which is significant. I'll also get taller sidewalls and a better overall tire in the process. Ignoring the cost, what's the potential downside?

Also, for the record, I like a firm ride as much or more than anyone else I know. I love the feel of a sports car, so I'm not expecting the TTS to become a cruiser, but I think it's reasonable to expect that a little tuning can customize the car more to my tastes and make it a bit more livable as a daily driver.

SimianSpeedster

Thanks, Chuck. How would you say the Contis ride compared to the OEM 19" tires, and which variant did you have (Bridgestone or Hankook)?

SimianSpeedster

Thanks again, Jeff. I know these things are easier to experience, but not always easy to describe. If you don't mind a quick quiz, on a scale of 1-10, how would you rate the following:

Road Noise Before & After
Impact Harshness Before & After
Wheel Movement/Busy-ness Before & After
Overall Ride Comfort Before & After

Lastly, is the TTS any better over tar strips, broken pavement, RR tracks, etc. with the new setup and, if so, how much would quantify the improvement that you've experienced?

n828cl

We had the Bridgestones for the 3k km in Europe, and I had the Contis installed before driving it in this country. The roads were much, much better in Europe, so it's difficult to make direct comparisons. The Contis do seem quieter on most surfaces, but I don't recall any undue harshness with the S001s even on cobblestones. If I go to Brainerd in April, I'll put the Bridgestones back on and see what they're like on Minnesota potholes.

- Chuck

Glisse

Just read a review of the new M-B E Class, being driven in Lisbon (not good roads) which found the same thing. On larger impacts, comfort setting couldn't cope, and he had to change to Sport mode: firmer ride, more jiggles, but much better control on really bad surfaces.
Steering feel/weighting, in theory.

I like your logic and would probably do the same thing in your situation. The other issue, and the primary reason most of us tick the option box, is looks. It is the car designers that draw up larger wheel designs and options, not the chassis and suspension engineers. I confess to being shallow, I like the look of the TTS on 19" wheels. That would be my downside.