Hi All,

I am currently on a set of Winter wheels that I invested in earlier in the year when I discovered that AWD on its own doesn't help if all 4 are slipping.
I have just ordered a pair of new summer tyres and have a pair of part worn ones from last year and will shortly be swapping them back on (assuming summer decides to arrive).
So, I have 2 questions;
Which is the best axle to put the New Pair of Summer tyres on for an AWD vehicle?
Given that the winter tyres have a preferred direction of rotation, an I use one of the Winter wheels as a spare rather than the current space-saver?

 

SiHarvey, I am going to get to your answers, but one bit of caution to think about before going too far with things. With an AWD car (unlike a FWD or RWD only vehicle), keeping tires that are the same diameter (not necessarily the same width tire) on all 4 corners is critical. To not do this will almost always result in some form of driveline damage. With this being said, there is some allowance for wheel size difference (this is what allows the car to make turns since the wheels are spinning at different speeds). So, when you are replacing 2 tires and using 2 older tires, look at how much wear is on the older tires. If they are at 50% or more tread, then you should be golden. Less, well, now we start gambling with how much difference will the car tolerate. This 50% is my own rule. You will not find anyone that will give you a specific number. Hence why most tire places will not sell you 2 new tires for an AWD car for fear of being sued to fix the driveline of a car. So, this is your call.

Now, I will tell you that you can do this as I have done it myself. But, I used the above rule to minimize any chance of problems. I would recommend putting the new tires on the rear for the main reason that most of your power (60%) goes to the rear and those tires should have more traction to handle the extra power.

As for using a winter tire as a spare. This is the problem I see. The winter tires have a direction of rotation, what is going to happen if you turn them the wrong way (normally the tire will come apart due to the cords shifting inside the tire after some driving)? If you are needing it only to drive say 10 KM to a tire shop and you can keep the speeds down, then by all means, go for it (granted, I wouldn't use it for normal use after that, even if it is turning in the correct direction). But, if you are thinking that you would need to drive further than that, then I would be looking at something different for my spare.

 

Thank you Thermo, that aspect had not even crossed my mind! Also I am on the stock 16" rims, so I guess it makes a bigger difference. I had thought to spread the cost, so replace the 2 worst and then the other 2 after a couple of months - they are ~4mm at the moment, I would normally replace 2.5 - 3mm.

I have committed to a pair at the moment, what is your recommendation (I wouldn't sue, honest!), would I be better off sticking with the Winter set until I get a set of 4 (probably next month) - UK weather is pretty ropy at the moment anyway - or going 2 new/ 2 old for a couple of months?

Certainly from your comments, I think I will scrap the idea of using the Winter as a spare! If I have to keep the speed down anyway (and have a 50% chance of mucking up a perfectly good tyre!) I may as well stick with the space-saver.