Section width VS compound for traction and handling

Wurf

Member
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2010 CX9 Blue
From what I understand, it's not so much the width of the tire that determines traction as it is the compound. In other words, a 215 section width vs a 245 - if the 215 is a DOT legal track tire and the 245 is rock hard, long wear, all season, the 215 will give you more traction in a straight line and in lateral g's.

That being said, what's the consensus comparing the rather sticky 140 tread wear rating, stock Bridgestones to a tire with a higher treadwear rating of say 240, still with a traction rating of AA, but in a wider section width?

What I'm getting at is it would seem Mazda decided to equip our cars with super sticky, relatively narrow section width tires. This gives you the advantages of lower rolling resistance and therefore better mileage with great traction and handling at the expense of rapid tread wear.

When looking at replacements, if you want to increase the section width and sacrifice some rolling resistance for more traction, how much trade off is there in the compound? At what point are you loosing traction to the stock tires even though your section width is wider?

I'm specifically looking at 235/40/18 for RX8 rims in the spring. I would run an all season if somebody told me I'd give up nothing in traction and handling to the stock tires due to the increased width, but I just don't know if that's the case.

Perhaps just a tire below the Extreme performance level is the limit. Something like the ultra high performance level and that's it. Anything longer wearing and you're giving up traction compared to the stock tires.

Anybody have some experience with this they care to share?

TIA
 
With the stockers, you got more steering feel and the tires were decently sticky to me. When I got RX-8 wheels, they came with 225/40 Kumho SPT tires and the only trade off was the tires weren't as sticky and rolling diameter was a tad smaller. I upgraded to 235/40 Nitto Invo's and those tires were grippy when warm and dry out, but you lost a little bit of steering feel. I now have 245/40 Kumho SPT's, less steering feel but absorbs bumps nice. As for gas mileage, gas mileage hasn't really changed for me.
 
Treadware is hard to compare from company to company because each tire brand has a different method of measuring tread wear but use the same scale. Therefore a Kumho with a wear rating of 140 might wear and grip differently than a Bridgestone with a wear rating of 140.

Also as you increase section width there will be more grip, not less.

Running all seasons of any width will never be able to provide you with a similar amount of grip and feel in comparison to a cimmer tire. Summer tires are stickier (in warm conditions) and have stiffer sidewalls for better cornering.

You shouldn't be worried about rolling resistance with your tires either. Your wheel assemblies are meant to be as frictionless as possible so the amount of friction increase due to an increase in tire size is tiny. However, under braking they will heavily increase the amount of friction and stopping power.
 
245/40 - won't those rub on stock suspension at the rear? Did you roll fenders or not? I'm definitely not interested in modifying the suspension or rolling the fenders which is why I've been pretty set on 234/40 even though it's a tad smaller rolling dia than stock 215/45.

It would appear based upon responses above that if I want to keep the steering response and handling I should simply stick with a summer tire and enjoy the additional grip from the wider section width. Utilizing a less sticky, higher wearing tires won't give me comparable performance even if they are wider than stock.

I guess the choice now is simply picking a tire that has good grip and if I want better wear, I'll just have to go by ratings and feedback and try them and see.
My stock Bridgestones are at 17K and they are not working so well any longer. One pair is past the wear bars and they are in back. The fronts are pretty close to the wear bars.
They slide around pretty bad right now, but it's in the 40's where I live, so no surprise. They will be swapped for snows in the next week or so.

Any opinions on the Nitto NT05? I am looking at those for next year, and maybe possibly the Hankook Ventus Evo - reneging on my thoughts about not buying a Korean tire.
For the money, they both look like great tires. The NT05 is softer and higher performance but the Hankook will most certainly last longer.
 
Wurf, there is much wisdom in your observations. My stock RE-050's gave up the ghost at 27,000. I thought that was pretty good mileage from what has been reported on this board and others, although I drive this car very hard. We have just enough cold weather here in the deep south that I thought I would want to move in the direction of a UHP all-season tire. So I did the research and all things were pointing to the Pirelli PZero A/S. I purchased them in the same stock size.

I think I made a mistake. Even though they have some of the best, maybe THE best A/S traction and are absolutely superb in the wet, they do give up a considerable amount of straight line launch traction to soft, sticky true summer tires. They are harder and now that I've got about 17,000 miles on them they are showing almost no wear. But, they break loose very easily. In fact, I can break them completely loose in second gear just by rolling into WOT. A flat shift from second to third burns them -- yes, burns them, not just chirps or a short loss of traction -- burns them almost all the way through third. And these are damn good A/S tires.

If I had it to do over again, I'd go back to true extreme summer tires in this warm climate where we rarely see snow or ice. My bad.

I don't mind paying a bit more, so if I EVER wear these out, I'll probably look at something like the RE-11 Bridgestones.
 
Yes, my rears are rolled. You might need to roll your rears for 235/40's as well. Under hard compression, they'll rub slightly from what my friend told me.
 
Got 26K out of the stock tires on my 08 MS3 commuting a lot , bout got into accident first snow up here in WI. Car ran a 13.61 @ 105 , come Nov after scare I put on 225-45-18 A/S WS4 Avid Yok, went to track in the spring and was able to run 13.56 105. I now have 42K on the tires and went to the strip 3 months ago and could still run 13.9's. They are getting hard now and do spin more if I put my foot in it and I am not thrilled about this winter but I still have about a 16th to go before I hit wear markers and I am going to probly drive wifes Minivan when it snows.
So A/S don't always take away performance at least in a straight line!
 
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Since I'm running dedicated snows for winter I'm not really considering an AS tire. I just wanted it as a reference for comparison in trying to figure out what the wider width would give me with this car.

It's going to come down to what level of summer tire - Max performance or Extreme performance.
 
Its all about give and take. You can't have the tire life you want with sticky tires, and you can't have the traction you want with long lasting tires.

The best thing to do is have 2 designated sets. Your summer performance and your winters (relative to your location and if you even have a "winter"). But obviously you've got to buy all that stuff

For me, the oe tires lasted ~33k miles. After that, got the eagle gt's because I wanted the better lifespan and they are also a little more forgiving on bumps and potholes than the stockers were. I don't track or launch so the grip feels the same to me that it did on the stocks

In my perfect world I would have a designated winter and summer set, but alas I do not

Edit: didn't even read your last post, oops

In your case since you already have 2 sets, get the stickiest tire you can get. That might mean getting a thinner (215mm) width to get a stiffer sidewall

I'm not too privvy on tire&wheel combinations, but to me it seems that the best traction would partially come from stiffer sidewalls, and that is achieved by having a tire width that best matches the wheel width with no lip overhang or underhang, so pretty much sidewall is flush with the face of the wheel

That's just a personal theory though
 
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Agreed 215mm section width is optimal on the stock tires but those will be mounted with snows from this point onward and my RX8 rims will get summer tires in the spring.
This is the reason I am looking at 235 section width for new tires as the RX8 are 8" wide. Not really sure what the optimal section width is for a 8" wide rim but I bet a 235 will work nicely.

Long lasting and sticky are relative terms and for me, the relation is the stock Bridgestones. They were sticky and they wore quickly with an advertised 140 tread wear rating. I'm going to shoot for something slightly less sticky and hopefully with better wear using feedback, wear rating numbers, and product classification from the tire retailer ( Maximum performance or Extreme performance ). Probably shooting for something at least 200 to 250 for tread wear rating understanding it's hard to compare different tire manufacturers in this regard.
 
Wurf,

Youre in luck - I also have a MGM with charcoal painted RX8's that I just put on a set of Nitto NT05's. (Yep - that's my winter set up here in SoCal(rockon)) They fit perfect and no rubbing for me (I'm on the stock suspension) While they are 200 treadwear, as we all know you can't compare that to the 140 treadwear on the stock Bridgestones being from a different manufacturer but we'll see when I get more miles on them how they compare treadwear life wise. If they last as long as the stockers did I will be happy with that as these NT05's are in the extreme category and are plenty sticky for a DD.

I will take some pics and respond back for you as soon as I can.
 
Excellent info JV - thanks!
I virtually get to see what my car will look like next spring!

What color did you go with for painting the wheels by the way?
Right now mine have rattle can, Duplicolor silver wheel paint, but it came out rather crappy and I plan to repaint them again before mounting tires on them.
Tried the Duplicolor graphite on a test patch but didn't care for the way it looked alongside the MGM color. There's too much blue in the MGM I guess.
Thought about bronze but didn't really care for that either.

How do you like the NT05 thus far? I've read they are quiet and even work really well in the rain. I would expect the car to have much greater lateral G's than stock with that setup.
 
I rattle can painted mine also. Color is a dark charcoal with matte clear coat. They turned out good but I put alot of time into the prep and a 3 step painting process over several months as I had time on the weekends to deal with it so I had high expectations. You're right about gunmetal and MGM - I felt the same way as it just takes on the color of the car without enough contrast so I needed to go darker but everyone and their mom seems to be driving every kind of car around here with black wheels so I wanted to stay away from black but still go dark to give contrast but keep them light enough where the tire would be darker than the wheel. I did a test panel with a few color samples - I will upload a pic of that as well when I get a chance.

As far as the NT-05's so far, I only have a few hundred highway miles on them but as far as I can tell the sidewalls seem slightly stiffer than stock which I like. I wouldn't call them quiet as they have more noise than the stockers when they were new but they are not loud by any means. They don't have the initial turn in response as the stockers did which may be attributed to the small increase in scrub radius (this difference in feel is very slight), I feel the performance is all around better but all this can be attributed to a combination of a wider tire and lower/stiffer sidewall compared to stock. Can't judge wet performance as I haven't driven in the rain yet.

Regarding the size difference from stock to 235/40, overall diameter has only decreased by 0.2"/6mm (0.9% shorter than stock) so when your speedo reads 60mph, actual speed will be 59.4mph (used this calculator for info: http://www.rimsntires.com/rt_specs.jsp )
 
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