A funny tire sizing question for 850's

[northernlights]

I recently had to replace two tires. I developed a bad thump which turned out to be because one tire (a 2007 vintage Toyo) was no longer round, and was at risk of exploding. My vehicle has the 205/55R16 'upgrade' size which means it is now easy to find replacements off the shelf as this size is used by mass-produced late-model Mazda 3's and Honda Civics, amongst others.

I bought a pair of Bridgestone Ecopias because they were available, and being H-speed rated, I thought 'They can't be all bad'.

Big Mistake. I never thought replacing two eccentric, nearly dead tires with new rubber could have such a negative impact on handling. Oversteer is now a huge, huge problem, and as I am not ready to start dirt-tracking I need to replace the new tires with something better. As the front's don't look so great, I might as well do all four. I think the short term solution is to put the new tires on the front to balance it better - or remove the rear sway bar! It's really that bad.

Because I can't bare to leave better enough alone, this leads to my question. Since I replaced the front springs and struts, I have no rubbing issues at all with the 205/55R16's. This is part of the problem - new front springs with Koni's and rear Bilsteins allows the car to easily overdrive non-sticky tires. (Did I say what a bad idea the Ecopias were?) I've thought about going back to 205/50R16's to improve handling, but the risk to the wheels has me concerned.

As an alternative, has anyone experimented with 215/50R16's? I realize this is a strange size, but they were OEM on Contour SVT's so they are available. They are also half way in diameter between the 205/50's and the 205/55's, so there is more rubber to protect the wheels, and the rubber is wider which is always a plus.

[JRL]

Shocks don't match up at all, that is your first issue, the Konis and Bilsteins have a totally different way of compression and rebound, they work completely differently
Try a set of Conti DWS tires, you will like them 205/55/16 and if I were you, get rid of the rear Bilsteins for matching Konis

[northernlights]

Shocks don't match up at all, that is your first issue, the Konis and Bilsteins have a totally different way of compression and rebound, they work completely differently

I have to respectfully disagree about the Koni vs Bilstein, especially the assumption that they are completely incompatible. Which, in the event it is not obvious, are the Koni Sports (in front) and Bilstein HD/B6's in the back.

Here's a little presentation from Koni with some good shock dyno data for a direct comparison, albiet for a Honda.

Prior to the tire swap, using sorry looking 205/55R16 Toyo Versado LX's at 40 psi with the Konis set at full soft, the handling was outstanding. There was slight oversteer near cornering limits, which to me is where handling is best.

This went completely to pot after the rear tire change to the dreaded Ecopias. Again....dumb, dumb, dumb move on my part!

I chose the Bilstein B6's for two reasons. Firstly, based on the data from Koni, the Bilstein B6 which they tested had a little more low speed compression compared to the Koni Sport at full soft. This is what I believe is needed to help control weight transfer under acceleration, and is the part which is non-adjustable in the Koni's.

Secondly, adjusting the rear shocks is a pain.I would probably leave them alone after installation, so the benefits of a rebound adjustable rear shock seemed minimal.

Ahem...any thoughts on the tire question?

[precopster]

I just put 2 of these Dunlop SP Sport Maxx TTs on the front of my 2000 V70 NA and have covered about 3,000kms so far. I am very impressed with the quiet tread and extremely comfortable ride. I chose 205/50/17s and spent a small fortune on them after chewing through too many cheap tyres. They are very comparable to anything from Conti and have just won a local sport tyre comparison with other sport tyres.

http://www.dunloptyres.com.au/dotCMS/Ty ... m=nPerPage

Did I mention they handle brilliantly when at the limit?

[matthew1]

Northernlights, I don't have firsthand experience with that tire size, but they split the aspect ratio difference between OEM size 205/50/16 and replacement 205/55/16, while offering more rubber on the contact patch. That's close. I wouldn't worry about it, it's not a big change. As always, they'll be candidates for rubbing, but if you've been messing around with tire sizes (and are a regular here at MVS) you know that already.

[matthew1]

Prior to the tire swap, using sorry looking 205/55R16 Toyo Versado LX's at 40 psi with the Konis set at full soft, the handling was outstanding. There was slight oversteer near cornering limits, which to me is where handling is best

Good tip. Tires and shocks are expensive, and input like this can help others make the right buying decisions.

Good discussion, guys. I love this stuff. So much so I grabbed some details on the three tires mentioned in this topic. Text taken from TireRack.com and Toyotires.com.



Bolds are mine, what I found interesting or noteworthy.

Bridgestone
Ecopia EP422
Grand Touring All-Season

The Ecopia EP422 is one of Bridgestone's ecologically oriented Grand Touring All-Season tires developed for the drivers of coupes, sedans, minivans and small crossover vehicles looking to combine year-round traction, handling and comfort with reduced environmental impact. Ecopia EP422 tires are designed to enhance vehicle fuel economy by reducing tire rolling resistance along with the vehicle's carbon dioxide (CO2) emissions while delivering year-round, all-season traction, even in light snow.

The Ecopia EP422 uses an all-season tread compound featuring Bridgestone's unique NanoPro-Tech (Nanostructure-Oriented Properties Control Technology) to reduce rolling resistance and energy loss while maintaining dry, wet and wintertime traction.

This compound is molded into a symmetric tread design that combines notched shoulders and intermediate ribs with independent center blocks for dry road tracking and traction. Four circumferential grooves are designed to help water flow from under the footprint to resist hydroplaning and enhance wet traction while notches and sipes increase the edges that bite into light snow. The tire sidewalls feature Bridgestone's Fuel Saver compound to further increase efficiency.

The tire's internal structure includes twin steel belts reinforced by spirally wrapped nylon on top of a polyester carcass to blend ride comfort and durability.

Toyo
Versado LX
Standard Touring All-Season

This luxury-touring tire for sedans and minivans delivers long tread life and a comfortable ride. It is available in a T-speed rating.

In addition to our limited warranty, the Versado LX also comes with an 80,000-mile treadwear warranty.

Asymmetric, Non-Directional Tread Design
Enables cross rotation to reduce irregular wear.
Larger Contact Patch on Outside Tread
More tread to the ground increases lateral stiffness and traction.
Higher Sipe Density on Inside Tread
More biting edges for increased traction in the snow.
Silent Wall™ Technology
Reduces pipe resonance, resulting in a quieter ride.
Multi-Wave Sipes
Minimize irregular wear for a smooth, quiet ride.
Increase all-season traction

Dunlop
SP Sport Maxx TT
Max Performance Summer

The SP Sport Maxx TT (Touch Technology) is Dunlop's Max Performance Summer tire developed for the drivers of sports cars, sporty coupes and high performance sedans. Dunlop Touch Technology combines sophisticated tire development and manufacturing techniques to enhance road feedback and driving precision. Like all summer tires, the SP Sport Maxx TT is not intended to be driven in near-freezing temperatures, through snow or on ice.

The SP Sport Maxx TT uses a motorsport-inspired tread rubber compound molded into an asymmetric design that fine-tunes the rubber contact with the road to blend dry road responsiveness with wet road grip. Dunlop Multi-Radius-Tread Technology distributes footprint pressure effectively across the tire and allows the footprint shape to change more smoothly as it moves from a straight to a curve, leading to better control and more precise driving. The tire's internal structure includes twin steel belts reinforced by Dunlop's JointLess Band (JLB) spirally wound Polyamide cord to provide high-speed durability and enhance ride uniformity. Kevlar® fiber is encased in the bead area's reinforcing rubber to create a firmer sidewall with a tighter connection between the tire and rim to increase stability when cornering, as well as enhance performance when accelerating or braking.

[northernlights]

OK...as the topic seems to expanded a bit, I thought I'd post a little more detail so that nothing important is missed, or inaccurate.

Firstly, here are two pictures of the alluded to 'good' Toyos. I am posting these because they appear slightly different than what is currently available. My old ones were H rated, not T rated as the new ones marketed by Toyo. The Versado LX II might be the new equivalent to these as they are also H rated.





And, a shot of a lurking Koni Sport plus a spring tag, which deserves a long explanation:



When I replaced the front struts, I replaced everything, down to the fasteners as I felt that 19 years was probably enough. This includes the front springs. With worn out stock struts, and I suspect sagging springs, bottoming was an everyday event and I could frequently hear rubbing in the inner fenders (and the marks are still there...). I started to look into finding some stock replacements, and it seemed that I had at least three options based on the following part numbers and descriptions (although I never did find the colors as claimed...):

3546640 AT no AC (supposedly White)
3546641 AT with AC or MT no AC (listed as Blue)
3546642 MT with AC (allegedly Green)

This is where it got interesting. I assumed that a car with AC weighs more than a car without AC (not a big stretch!). I also assumed Volvo wanted all of the 850's to have the same static ride height, and that they would use the same spring material to save on manufacturing and design costs. If all of those presumptions are true, and if I were making springs, then I would change the free length slightly to compensate for slightly different front end weights. In other words, if you design two 120 lb/in springs, one of which needs to support an extra 50 lb at the same ride height, I would wind that one 50/120 longer (about 13/32") so that they would be identical when installed.

With that in mind, I concluded that the MT with AC spring would be wound slightly longer than the MT without AC spring, which coincidentally was the same as my AT with AC spring. I therefore assumed that substituting the -6642 spring for the stock -6641 spring would probably give me an ever-so-slightly higher installed height, which I hoped would help prevent bottoming and rubbing.

I came across a set of new Volvo OEM -6642's for a good price, bought them, and installed them with the Konis.

Interestingly enough, poking around a bit online helped to at least confirm my suspicions, or at least helped me convince myself that the logic was sound. More specifically, I found references from Skandix to free heights for two of their replacement Volvo 850 springs. The -6641 was lsited as having a 435 mm free length, while the -6642 had a 445 mm free length.

I measured it before and after, and after a few months in service I still have about 8 1/2" under the front air dam instead of 8". While this may be purely due to the new springs as opposed to the change in part numbers, new springs plus the front Koni sports made the bottoming out go away along with the inner fender rubbing. And like I mentioned before, the handling was outstanding until I put bad tires on it.

[northernlights]

Try a set of Conti DWS tires, you will like them

I ended up buying a set of four Continental DW 205/55R16's about 3 weeks ago. I looked at the DWS type, but where I am there is never, ever, ever any snow, so I thought I'd give the DW's a try.

JRL's been recommending these tires for a long time, and I definitely see why. Grip is outstanding both dry and wet, and they aren't noisy. Given how good these are for the price (about $100 each at TireRack), and assuming you don't need to run them in the snow (ever!) I think these are well worth trying. We'll see how long they last with a careful eye on alignment and a reasonable rotation schedule. Treadware rating is 340, which is pretty darn good for a W rated summer tire.

[matthew1]

I had the DWS on my '04 V70 R, and grip was fantastic, even with the "S" designation. With those tires the car was a Beast.

[northernlights]

Try a set of Conti DWS tires, you will like them

I ended up buying a set of four Continental DW 205/55R16's about 3 weeks ago. I looked at the DWS type, but where I am there is never, ever, ever any snow, so I thought I'd give the DW's a try.

We'll see how long they last with a careful eye on alignment and a reasonable rotation schedule. Treadware rating is 340, which is pretty darn good for a W rated summer tire.

I replaced the Conti DW's today. I got 29k miles out of them, although my rotation schedule was anything but reasonable! Honestly, I was rotating them at least as often as I change the oil, i.e. every 5-7k miles, because the fronts would wear much, much faster than the rears. And...my alignment was done in my driveway with string, jackstands, masons levels, machinist rules, and an understanding of geometry, so you'll have to decide for yourselves as far as the fidelity of my data. But, in all fairness I spent a bunch of time setting the toe to as close to zero as I could which I believe tremendously helps with tire life. It is amazing how far off the toe can be off before one can tell while driving, and I think the alignment shops know this, which means who knows what they really set it to.

After brief experimentation at the beginning, I maintained stock air pressures of 230 kPa/210 kPa F/R for the operational period. Yes, I have a strange pressure gauge.

(aka 33.4 front and 30.5 rear, if I must)

This is what they looked like at the end....there wasn't much left.





Even at this point, the handling was still good in dry weather, but wet was a different story.

They were replaced with a set of Bridgestone RE 760's in the dreaded and greatly feared 205/50R16 size, but that's a different post!