Have fun and be safe, I have fond memories of living in Bay area and exploring all over in my crx as a poor college kid:=)Well I have one pair of chains and I’m going in to temps bellow 35°F. I’ll report back to let you know how my Coopers do! They have the 3PMSF symbol and I’ve seen videos of guys with wider tires than mine absolutely destroy in the snow and ice with their Dusters and 4.2 Ravs. But we shall wait and see. Thanks for the detailed advice and info. Always appreciated.
That is quiet the research on the subject, I am impressed and happy to learn. Seattle area is not bad usually but as soon as we head a bit east into the mountains or south to Portland/California I think sometimes they are mandatory, so I am not sure if we will have a choice.In regards to your RAV, I don’t think you’ll find much use for chains. If my past experiences with KO2s are any indicator, you’re going to scoot right along in severe winter weather. A snatch strap or tow rope could come in handy pulling others out of the ditch though 🤔
I should emphasis it‘s not merely the KO2s that are going to work so well for you, but the benefit of narrower tires as well.
Winter traction is about mitigating the effects of hydroplaning right down to the micro level. In the ’60s NASA developed a formula for calculating hydroplaning of aircraft wheels: 9(√ tire pressure). The NHTSA has revised it slightly in recent years to accommodate the greater diversity of automobile tires, something closer to 10.35(√ tire pressure). As a narrower tire has a smaller air chamber than does a fatter tire of the same diameter, narrower profile tires come typically specified for a commensurately higher air pressure to carry the same vehicle weight. My Nokians for example are specified for 32-50psi, I run them at 41. What this means is my RAV doesn’t experience hydroplaning until a whopping 66 mph, whereas a RAV4.2 equipped with 235s and Toyota’s recommended 29psi has lost control at just 55 mph at a water depth of 1/10”.
But severe winter driving introduces even greater threatening forces than just liquid H2O; slush and ice. But each of these is still fundamentally a water problem, in that the tire needs to evacuate a non-compressible medium as quickly as possible.
With slush, the tires have to evacuate a greater volume of water because water expands as it freezes. It also becomes more viscous, about x8 more so below freezing than typical summer temps. A smaller contact patch for a given vehicle weight motivates slush to egress the tire’s foot print with greater force. For a 225 that's about 25% greater force than a 235 series tire.
And finally, this 25% greater lbs/sq-in is where a 225 will hook up on ice when a 235 simply won’t. When the sipes have done their job directing water into the tread void or out of the footprint altogether, all you have left is the tread face and how hard your vehicle is pressing it onto the ice. The 3PMSF symbol guarantees your rubber compound will remain pliable enough in sub-freezing temperatures to conform to micro-surface features of the ice.
All this to say that’s why chains are a waste of money for you Mastee, but might be a good idea for Mistermike
Interesting thing to note: a 215 series tire would be better still for winter driving for RAV4.2s, but many of us have conceded this benefit to run a single tire year round.
It's about temperature, not snow. Winter tires should be installed when you expect temperatures to fall to 7C or colderwww.theglobeandmail.com
Nokian Tyres conducts comprehensive and careful tests on its products in real-life environments.www.nokiantires.com
Yah the chain requirements up here are a little confusing. It says chains are required as we’re making our way up to mammoth but other signs say snow tires and 4wd are ok. I saw a bunch of Subaru’s kept on going so I decided to follow and see how it went. Roads are completely snowed/iced over getting in to town with temps right now around 10°f. Tires and the Rav’s 4wd have been really impressive so far. No sliding, great grip, and breaking have been great. Will upload a vid later this weekend. So far so good🤙🏼That is quiet the research on the subject, I am impressed and happy to learn. Seattle area is not bad usually but as soon as we head a bit east into the mountains or south to Portland/California I think sometimes they are mandatory, so I am not sure if we will have a choice.
Thinking about ordering a curt class III hitch to be able to use an aluminum basket or a bike rack (no towing) since I will be taking the cross bars off. I will skip the trailer wiring or scavenge it off our matrix (it has never hooked anything and probably never will before I sell it), I haven't checked but I hope the tail sockets are same
Yes i agree with you and totally appreciate your experience and knowledge. For my situation right now my Cooper AT3 4s 3PMSF tires has definitely got me through the muck which i am actually surprised. I was just worried about my my tires being too wide like you said earlier. But if I was living in this weather on a daily basis or traveling in this for a long period of time, I would definitely invest in dedicated winter tire. All that being said, the 4wd system is legit. I was skeptical at first, but after this drive through the mountains with heavy snow and ice I am thoroughly impressed.Washington chain laws: https://www.wsdot.com/winter/tires-chains.htm
California chain laws: https://dot.ca.gov/travel/winter-driving-tips/chain-controls
There exists some woefully dated material in either State’s language regarding snow tires or traction devices;
1) All-Season tires are extraordinarily inadequate for winter driving in the West.
2) Tires labeled M+S are only MARGINALLY better than All-Seasons, but still poorly suited for the job.
WA and CA recognize the above as adequate winter traction tires. This today is certifiably cooky-dooks, absolute non-sense and a total inability to keep up with modern technology.
3) 3PMSF rated tires should be the MINIMUM requirement for driving on snow and ice.
4) A dedicated snow tire is still leagues ahead of an All-Terrain tire labeled 3PMSF.
I used Toyo ATII AWs for awhile on my FWD Escape. If you don’t know that’s an All-Terrain tire rated M+S and 3PMSF. It met German requirements for a snow tire and I had to chain up to negotiate the worst mountain passes. Second winter I switched to dedicated winter tires. That year was the worst winter in Europe in 70 years and my chains were never unpacked! We had a phenomenal winter that year my wife and I, traveled a great deal more on much worse roads and passes because the Escape plowed through the snow and ice like a tractor.
Bottom line: You‘ll have absolutely no reason to ever put chains on your 4WD RAV with appropriately sized WINTER TIRES. Running All-Terrains with at least the 3PMSF should see you through most of the muck . . . but mileage will vary provided tire models and sizes. Using anything less during winter driving is dangerous and I would anticipate using chains frequently.
I don’t mean to cause anyone to doubt their capabilities, I‘m just trying to explain the limitations of tires at their extreme winter envelope.I was just worried about my my tires being too wide like you said earlier.
I agree.... each time I look at my videos, I think the same thing.The video always makes the hills look flatter than what they really are irl for some reason.
I caution owners of RAV4.2s to run Toyota's recommended air pressure. It's expected of you when running OEM tires, but Toyota has no legal expectation or blanket knowledge of all aftermarket tires, especially in plus sizes.The recommanded pressure for a RAV4.2 is 29 psi.
This is because automobiles are getting bloated and fat. As a nuematic tire, higher pressures are required to carry the additional weight of the vehicle. The additional air doesn't require a corresponding weight penalty. Better fuel economy is achieved by thinner sidewalls and better construction materials.I observed that most manufacturers tend to put the tire pressure higher and higher (up to 40 PSI) since about 10-15 years. Even a small compact car that the recommanded tire pressure was 28 PSI 15 years ago is now at 33-35 PSI.