sub-compact AWD vehicles HR-V C-HR CX3

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Do all these new little AWD vehicles have tight tires (tolerance)? Like, we replace tires, it must be all 4 at the same time?
 
I don't know the exact setup of these two mico-CUVs, but here's how most great AWD systems tend to work, with my logic for saying that even tire wear all around would be important.

Front and rear are open differentials; however, stability and dynamic control (TCS and VDC, as an example) will not only cut power when wheel slip is detected, but selectively brake individual wheels that are sensed to be slipping. So, a minor difference in tire diameters likely won't have any affect, but mixing worn tires with new, left-to-right, might lower the marginbto when brakes are applied, potentially increasing wear. You'd have to research how their traction control scheme is setup.

The bigger concern, and likely more prevalent condition, is uneven wear, front-to-rear. In this case, and in very simple terms, when the center "differential" clutch engages to connect the front to rear, it will slip and increase wear if the front tires are spinning at a different rate than the rear tires. Luckily, the clutch likely doesn't engage unless front-to-rear slip is detected, at which point the clutch would be cycling to transfer power anyway.

So, differential tire wear would lower the margin to engagement of traction control, but how much wear would be induced at how much differential wear is hard to guess. The overall effect will likely be less than for a vehicle that had a true center differential or limited slip differential(s), but I wouldn't risk it; I'd ensure even tire wear and replace all tires if on or more needs to be replaced and the rest are worn significantly more.
 
Not sure about the specific models, but I believe AWD systems generally require the tires be within 2/32-4/32"
 
Originally Posted By: gathermewool
I don't know the exact setup of these two mico-CUVs, but here's how most **GENERIC** AWD systems tend to work, with my logic for saying that even tire wear all around would be important.

Front and rear are open differentials; however, stability and dynamic control (TCS and VDC, as an example) will not only cut power when wheel slip is detected, but selectively brake individual wheels that are sensed to be slipping. So, a minor difference in tire diameters likely won't have any affect, but mixing worn tires with new, left-to-right, might lower the marginbto when brakes are applied, potentially increasing wear. You'd have to research how their traction control scheme is setup.

The bigger concern, and likely more prevalent condition, is uneven wear, front-to-rear. In this case, and in very simple terms, when the center "differential" clutch engages to connect the front to rear, it will slip and increase wear if the front tires are spinning at a different rate than the rear tires. Luckily, the clutch likely doesn't engage unless front-to-rear slip is detected, at which point the clutch would be cycling to transfer power anyway.

So, differential tire wear would lower the margin to engagement of traction control, but how much wear would be induced at how much differential wear is hard to guess. The overall effect will likely be less than for a vehicle that had a true center differential or limited slip differential(s), but I wouldn't risk it; I'd ensure even tire wear and replace all tires if on or more needs to be replaced and the rest are worn significantly more.


Auto-correct. Meant *generic* above
 
thanks for all the inputs... i can understand "got to pay to play" that's why our family is hesitated on these 3 models. we are kind of lazy; we have 2wd vehicles and we never rotate tire and we only buy 2 tires at a time LOL...
 
Well, what do you need the AWD for? My very recently sold '08 Civic with Blizzaks was pretty darned good in the snow. A FWD vehicle with even more ground clearance would do pretty well in moderate snow/slush/ice. It will certain brake as well as any AWD vehicle.
 
2WD with snow tires has never let me down in the snow!

In fact, I would have been perfectly happy if I could have got my Forester in either FWD or RWD.
 
Originally Posted By: gathermewool
Well, what do you need the AWD for? My very recently sold '08 Civic with Blizzaks was pretty darned good in the snow. A FWD vehicle with even more ground clearance would do pretty well in moderate snow/slush/ice. It will certain brake as well as any AWD vehicle.


Well what do you need AWD for? why didn't you get a FWD HR-V or CR-V when you sold the Civic?
 
Originally Posted By: UG_Passat
Originally Posted By: gathermewool
Well, what do you need the AWD for? My very recently sold '08 Civic with Blizzaks was pretty darned good in the snow. A FWD vehicle with even more ground clearance would do pretty well in moderate snow/slush/ice. It will certain brake as well as any AWD vehicle.


Well what do you need AWD for? why didn't you get a FWD HR-V or CR-V when you sold the Civic?


Probably the same boat I was in. I didn't want AWD and I tried to avoid it. But the Forester was the only vehicle on the market that met all of my criteria. So that's what I got even though it was AWD.
 
The HR-V should use Honda's Real-Time 4WD, which uses a simple PTO at the transaxle and a diff equipped with a dual oil pump mechanism along with a clutch in the back. Any differences between front and rear wheel speed will create a difference of oil flow between the 2 pumps which will engage the clutch to drive the rear wheels.

I'm not sure what Mazda uses, but seeing their past Ford/Volvo connection I wouldn't be surprised if it was an Haldex-based system.

I would try to keep the tires within 1/32-2/32" of each other and rotate religiously. I'm not sure if Honda or Mazda's system is as sensitive as Subaru or Audi, there have been reports of Toyota RAV4s with AWD trashing their PTOs due to sudden AWD engagement or tire size mismatch. It has happened on many Subarus with mismatched tires.
 
Originally Posted By: UG_Passat
Originally Posted By: gathermewool
Well, what do you need the AWD for? My very recently sold '08 Civic with Blizzaks was pretty darned good in the snow. A FWD vehicle with even more ground clearance would do pretty well in moderate snow/slush/ice. It will certain brake as well as any AWD vehicle.


Well what do you need AWD for? why didn't you get a FWD HR-V or CR-V when you sold the Civic?


I never liked the Civic - I'm 6' tall, 200# and the coupe was very uncomfortable to get in and out of. I did not intend to replace it so soon, but the '15 Legacy was being sold with just the right features and for a very good price. The owner was from North Carolina until this year, and had zero rust or corrosion anywhere.

AWD isn't necessary, but I like Subarus and their safety rating is top notch. It also came with the Eyesight package.

Finally, the Civic was great in snow for the vast majority of snow days, just as a midsize FWD sedan would be with snow tires. The stopping power was great. With that said, the tires still spun and traction was questionable at times when I was snowed in or while driving in deep, slushy stuff, where the AWD maintains a truer track. When it's really bad, like it was during last winter's one white-out-bad snow storm, I opted to take the Forester (also with Blizzaks) and was able to fully stop and then get going, whereas many people stopped and were then stuck. Not only was I able to get going in that nasty stuff, but I was able to do so safely - no perceptible wheel spin and no fish-tailing at all. It was actually pretty amazing.

//

Anyway, my question wasn't to convince the OP he didn't need AWD - it was to simply ask IF he needed it ever or just liked the idea of it. He's from CA, so unless he's doing some light off-roading, beach driving or taking weekend trips to the mountains, the need for AWD is all but nonexistent. I wouldn't purchase AWD just to get better going power in wet weather, personally.
 
I'd get AWD to pass through chain control, but AWD is nothing without the right tires. A Subaru on winter tires is nearly invincible. However FWD does fine in the snow with winter tires but you'll still need chains if local rules require it.

Just don't be that guy thinking a BMW X5M can make it up Highway 50 towards Tahoe on Bridgestone Dueler Sport run-flats but had to pull over since they were losing traction fast. This was also during a winter storm alert, we happened to be the unlucky ones in a Forester with OEM Yokohamas behind it.

Top Gear thinks BMW's xDrive is worthless.
 
I don't know what each car manufacturer says, download the owner's manual for each to find out.

I do know most tire shops will quickly tell you that you have to buy 4 at a time, usually while salivating and looking at your wallet. I have found a few that don't. If not I will bring in a single wheel and tell them it is for a 2WD vehicle. There is always a way.

2WD with Winter tires is a valid choice. A choice I make, well, every Winter. The other two vehicles in my fleet are 4WD and AWD, also valid choices. I live in hill country where the Winter temps go to freezing every night and leave black ice every morning. Old tires and 2WD are not an option.
 
Originally Posted By: nthach
I'd get AWD to pass through chain control, but AWD is nothing without the right tires. A Subaru on winter tires is nearly invincible. However FWD does fine in the snow with winter tires but you'll still need chains if local rules require it.

Just don't be that guy thinking a BMW X5M can make it up Highway 50 towards Tahoe on Bridgestone Dueler Sport run-flats but had to pull over since they were losing traction fast. This was also during a winter storm alert, we happened to be the unlucky ones in a Forester with OEM Yokohamas behind it.

Top Gear thinks BMW's xDrive is worthless.


I won't get to experience it this year, but I was always amazed at the 'premium' SUVs that couldn't navigate the hills of Syracuse. The city is out of money and really doesn't plow much. Even the main bus routes would go a day or two without being plowed. My Focus on snow tires always got me up the hill to the apartment without drama (except the one time I premature switched to allseasons in April). X5s ,CRVs, Lexus NX200 ... all of them had issues getting up the hills. Seems that their AWD system was too conservative and just gave up to soon.

Subarus didn't seem to have problems going up the hills as much ... but slid into the curbs just as well as the other AWD vehicles with not-proper tires.
 
Originally Posted By: nthach


Top Gear thinks BMW's xDrive is worthless.


When Clarkson reviewed the X6? To be fair, the X6 was wearing summer tires, so it would be pretty useless in the field and in the snow, as the xDrive-i can only do so much without traction at the tires.
 
Originally Posted By: 2008wrx
Do all these new little AWD vehicles have tight tires (tolerance)? Like, we replace tires, it must be all 4 at the same time?


I've never seen one that did not say in the owner's manual that all 4 tires must match, or damage to the AWD system may occur. Like said, a 3 to 4/32" difference probably doesn't matter much, but I suppose more could.

The same can be said for any modern day FWD or RWD vehicle with fancy traction and stability control systems. The owner's manual will say the same for them, all 4 must match for safety reasons.

This is one of the reasons I won't run super premium tires, especially on my AWDs. If you have an unrepairable flat with one of your $200 Michelin, you're potentially out $800+ for a whole new set. Sure you can try to source a used one of the same make/model and wear, but what's the likelihood of that working out.

This is a real concern for me given my work commute takes me through some nasty industrial areas with lovely tiny bits of metal in the road that you can't see until it's too late.
frown.gif


Trash a $100 tire and it's only half as painful.

Our our minivans, they're so tough on tires given their weight and how we use them, that I rarely rotate the tires and just replace the fronts when they're about 50%. Very rarely do I have the same make/model tires front/back on the minivan.
 
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Originally Posted By: UG_Passat
Originally Posted By: nthach


Top Gear thinks BMW's xDrive is worthless.


When Clarkson reviewed the X6? To be fair, the X6 was wearing summer tires, so it would be pretty useless in the field and in the snow, as the xDrive-i can only do so much without traction at the tires.

Yep - that was the episode. The Range Rovers were probably wearing Michelin 4x4 Diamaris/Synchrone or Conti's "sporty" SUV tire. As do many Range Rovers wear off the line.

It would probably be decent with a set of snow tires or all-seasons.
 
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