New tires, let's see what happens - Fuel Economy, Hypermiling, EcoModding News and Forum

IsaacCarlson · 10-02-2019, 03:47 AM

We finally got the new tires installed. Cooper Discoverer AT3 4S in 235/65/17. They are definitely bigger than oem and very meaty. I can bury my fingertips in the tread and my fingernails are no longer visible. They're deep and they fill the wheel wells nicely. The pictures online do NOT do them justice at all. These are very impressive tires. The oem size looked too small and left a lot of room inside the wheel well, so I decided to go up a size. I also liked the part about the speedometer being more accurate....and hopefully a tad bit better mpg on the highway. I noticed right away that the engine rpms are lower at the same road speed, which I like. (Not indicated speed, road speed. They're different)

I only bought 4 new tires since my wife likes the spare tire cover and it won't fit these without modification. The old goodyear tires (fronts) were absolutely shot. No tread left at all. I don't think I have ever worn out a set of tires that fast.(we normally get 60-90k on a set) I don't think we got 15,000 miles out of them. The tires were a mix match when we bought it and we put two new front tires (the goodyears) on last year. The rear tires were 14 years old and cracked/dry rotted something horrible, and they didn't even match each other (they must have been sitting on a shelf for a long time because there is no way they lasted 280,000 miles) The spare was a newer tiger paw which was in decent shape and has a good tread patern, so we kept it. We have been babying the old tires along since we got it and it's nice to have 4 brand new tires and a spare that has tread AND holds air. I may get a matching tire for the spare, but I have to see if the cover will even fit over it first.

Balance. I discovered that 4 of the 5 rims are bent (from the previous owner(s)! I put the worst offender on the spare and the next two worst rims on the rear. The only straight one and the least bent one went on the front. The really bent rim called for 3oz on the one side and 2oz on the other. I said "NO" and pulled it off and put the spare on that rim. Much better. Most of the weights called for were .75-1.25 oz, which is pretty normal. I dumped in some balancing beads for good measure (~3 oz of heavy airsoft bb's per tire). It rides great. Zero vibration at 80 mph, which really surprised me, considering it has bent rims. I will be getting new rims asap. I have never in my life seen a car with 4 bent rims that was not headed for the scrap yard or involved in a high speed rollover. mindblown This is nuts. On the hunt for new rims.

Anyway, the new Coopers are awesome. They are not a 'highway' tire but they are amazing on the highway. They handle well and the ride is smooth. And NO noise....nothing. I had read reviews where people said they were loud and kept getting louder....I think they had at least one bad wheel bearing, not loud tires. These are the quietest tire I have ever had, and that says a lot with the lack of sound proofing on the rav.

I drove on the highway and the troughs of water in the road didn't make a bit of difference with the new tires. I could hear the tires moving the water but I couldn't feel it. They made the road feel dry and that was a welcome change from the old tires.

Deep tread blocks and soft compounds will make a tire feel more squishy, but these aren't what I'd call squishy. They feel planted, and they absorb the bumps in the road, kind of like walking on good carpet. It's not hard or really soft, it's just comfy. They do squirm/roll a bit when zig zagging, but again, that's because of the very deep tread blocks and it will decrease as the tires wear. I'm running them at 38 psi, and I think that's going to be pretty close to their sweet spot. 40-42 psi might firm up the feel a bit, but being xl tires, it's not needed on the rav. These handle the same way my Cooper ST MAXX truck tires handled when new, and those had a large, deep tread. They've firmed up quite a bit as the tires have worn over the last 7 years. (Wow, those tires have lasted a LONG time!) If these last even half as long as the truck tires, I'll be a happy camper.

Traction. They seem to be quite "sticky" compared to the old tires and they really grab the road. I think the old ones were spinning just a bit on takeoff (before the rear locked in and traction control stopped it) even though we were using a light throttle. With the old tires on takeoff, the revs would jump up and then the rav would lurch and immediately shift to second gear. I suspect this was the front tires slipping a bit, as I have heard from other rav4 owners that theirs will burn the front tires without trying (2wd). We have the 4 cylinder, and while it may not have a lot of low end hp, it does have good low end torque. There was absolutely NO slipping today, even though it rained heavily most of the day.

That brings me to my biggest concern about buying these tires, the weight. I was worried that the extra weight would negatively affect acceleration and braking, but both seem to be largely unaffected. New tires are going to weigh a lot more than those worn out carcasses anyway, so I don't think you could really measure the difference the extra few lbs would have on performance. Most of the common tires in the factory size weigh 27-30 lbs. These weigh 35 lbs according to Cooper. I didn't weigh them, so I can't confirm that number. They did seem to be a few lbs heavier than the one good tire I kept for a spare, but I don't think the rav knows the difference.

Mpg. I know this is a big concern when people are looking at a different tire than is recommended. I don't know what the mpg will do. I'd like it to at least stay the same. I have been keeping track of mpg and have been averaging a solid 26 mpg over 5,000+ miles of city, highway, and off-road all combined. I'm willing to accept a mileage reduction if there is one, if it means having tires that we can trust to get us where we want to go safely. These have at least double the tread depth of oem/standard tires, and that's exactly why we got them.

Our tire pressure light has been on since getting the rav. I scanned it and most of the sensors are dead. I finally removed them today and replaced them with rubber stems. 3 sensors came out ok, and the other 2 broke off due to corrosion. Now I can plug in the tpms "jumper" and never worry about the system again. Woo hoo. As nice as it is to know a tire is low, I am not going to shell out cash to pay for 5 new sensors. I check my tires regularly as one should.

Overall thoughts after today? I like 'em. They should do very well this winter. Even with mismatched tires, the rav did extremely well in the snow last year, plowing 4 ft of snow and holding tight to the road. I can only imagine how it will do this year with these new meaty tires. Fall is in full swing here and the temps will be dipping below freezing before long. I will try to update as the weather changes and we get to test the tires in new conditions.