OT: Mixing tyres on an axle - good or bad?

[Pete Zahut]

For a total of about 15 years, I've been running around with an LPG tank in the spare wheel well instead of the spare wheel, and not a single puncture was had.

Four weeks into my ownership of an RX450h with a spare wheel and I get a puncture! Not only that, it's so close to the sidewall to make repair impossible, so tomorrow I'll be swapping one hundred and fifty or so of our Great British beer tokens for a new tyre :-@

The fronts are Bridgestones (can't remember exactly which ones and as it's dark, cold and wet, I'm not going out to find out) and the rears - of which this is one - are Dunlop SP Sport 270. I usually like to have all four tyres the same but I just can't afford to do that now, especially as all these tyres have a decent amount of tread. The Dunlops seem to get bad reviews, although in the 1,000 miles I've done since getting the car, I have to say they seem alright to me.

I'm just wondering if I should take the opportunity to change to a brand that I'm more comfortable with and that get better reviews, but that would mean there would be three different brands of tyre on the car and I'm guessing that that isn't really 'a good thing'TM

Should I stick with Dunlop to match its axle-mate or should I get something different and start the gradual migration to a whole set?

[The Natural Philosopher]

Not a good idea to mix brands on te same axle - differential braking performamnce.

I'd try and get a match to the other side or to the spare if I were you. Depending on which is least worn.

[tabbypurr]

+1, no sense chucking out a good tyre. Car mag reviews are often worthless IME

NT

[Pete Zahut]

Jim K formulated on Thursday :

I should have said that the spare is brand new but it's a space-saver tyre and only looks to be half the size of a 'real' one, so the spare is out of the equasion I'm afraid.

[The Natural Philosopher]

Well is the other wheel brand new? If so match it. It its 3/4 worn out buy 2 new tyres.

[Fredxx]

Perhaps this is the time to swap the spare saver with a full-fat one?

[Michael Chare]

I would be less concerned about not matching on the rear wheels. You can always test hard breaking but only after you have made a purchase.

[Brian Gaff]

Don't you find that the cost of tyres is somewhat high, considering that they must be made by a machine and hence probably quite cheaply. Brian

[tim...]

except that as it will not fit in the depression made for it in the boot it will now fill the boot all on its own

tim

[Jim.GM4DHJ ...]

They have never been cheaper just bought two for ?55 and they were H rated ...........

[Jim.GM4DHJ ...]

and I think there is still a lot of manual input in their manufacture .......

[Jim.GM4DHJ ...]

perhaps not...just watched youtube

[NY]

That is what I hate about spacesaver tyres. Not only do they give you wheel that has speed and distance restrictions, meaning that if you are in the middle of a long journey you have to get it repaired *now* rather than at the end of your journey, but they also design the boot so there isn't even space for a full size wheel.

My car has a deep depression in the floor of the boot, but it is tapered in such a way that a full size wheel will not fit. If the walls were the same diameter all the way down, a proper wheel would fit.

Not everyone is lucky enough to have a puncture during the day. Two of mine occurred as I was about to start a 200-mile journey on a Sunday evening. Thankfully this was when I still had a car with a proper wheel. Since I got one with a spacesaver, both have been during the way when I could detour to a tyre garage and wait while they repaired the punctures.

Goo-filled tyres as a replacement for puncture repair are even more of a con, because you have to replace the tyre and cannot get it repaired, even for a small puncture.

[tabbypurr]

Front brakes contribute about 80% of braking force. I don't know what the percentage of grip & thus braking force mismatch can be on rears, but its contribution to total brake performance is clearly some percentage of 20%, and probably little.

Rear grip matters more for cornering, where asymmetry is not ideal. But I don't know the difference in terms of numbers.

NT

[tabbypurr]

I expect when they were just tread-free strips of rubber they were much che aper.

NT

[James Wilkinson Sword]

You'll never notice the difference. I never rotate tyres, I never change two at the same time. I've had a bald tyre and a new tyre of different makes and styles on the same axel with no problem. A tyre is a tyre. You change one tyre when the plod moan at you or when it needs to pass an MOT. Even then you can do it temporarily :-)

[Vir Campestris]

Funny that. My spare is about 1/2 the width of the rears - and I was going to say well, of course the well will be designed to fit a full size wheel otherwise what will you do with it when you get a flat... mine _is_ big enough.

(Though TBH we've often got enough stuff in there on holidays for the lost space to be a problem.)

Andy

[NY]

I think the expectation is that you will put the flat full-width tyre on top of the boot mat rather than trying to fit it in the well. One car that I owned (it might have been a VW Golf) had a depression that was shallower than the full size spare but the carpet was shaped with a circular lump in it to accommodate the wheel - what a cop-out :-)

My Pug 306 had the spare wheel hung in a wire cage below the boot floor which was very easy to remove with lots of stuff in the boot, but it was a right bugger when the long bolt that secured the cage to the boot floor seized solid with lack of use. Now if they'd done the job properly they'd have made the head of that bolt a hexagon exactly the same size as the wheel bolts so you could undo it with the wheelbrace. But that was too simple. Instead they scored a wide, shallow groove all the way across a smooth cylindrical head, and you had to use a flattened end of the wheelbrace as a makeshift screwdriver blade to undo it. And that only worked as long as the bolt wasn't seized up. Even putting all my weight on the wheelbrace, that flattened end jumped out of the nick in the top of the bolt as soon as I tried to turn it. I was deeply embarrassed that I had to call out the RAC for help in changing a wheel - simple because I couldn't get the spare out. It took the RAC man a long time squirting WD40 liberally before he got it to move.

After that I got into the habit of undoing the bolt a few turns every week or so, and smearing grease in the threads all the way up. The RAC man said to be really sure, the best thing to do is to remove the bolt, put it in a vice and file a couple of flats on the head so there is something for a mole grip to get a purchase on, since Peugeot "screw head" approach was so crap.

That was the last car I had which had a proper full-size, fully-interchangeable spare that could be driven as far and as fast as any other of the wheels, because it was the same size of tyre, and the only difference was that it was a steel rather than allow wheel. Nowadays you are lucky even to get a bicycle wheel as a spare :-)

[James Wilkinson Sword]

Funny you should mention that. I had to call out the AA because I had a standard jack which wasn't the Peugeot shit, so I didn't have a tool to undo the bloody non-standard frog bolt to hold the wheel on. Neither did the AA guy, he eventually managed to cobble something together to undo it.

[ianp5852]

Mmmm. Just a thought. Isn't that an All Wheel Drive? The handbooks for both my 4WD recommend that all tyres be replaced at the same time.... and in, the case of the Subaru, specify the maximum difference in rolling circumference that is allowable between each corner. I resolved a similar situation to yours by aquiring a used tyre of similar degree of wear to the punctured one. I am also aware that Nissan have similar specification for the X-Trail. Might just be worth checking in the handbook Please reply to group - email address is not monitored Ian