Odd tyres....
Submitted: Saturday, Mar 16, 2013 at 17:18
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Member - Dalb (SA)
G'day All, Seeking some advice please,
I have a set of MickeyThompson FC11's on my 100 series auto TD cruiser and they are about half worn.
My rear left side tyre is the most worn and I would like to replace it with my still brand new (FC11) spare. Thus I will have, to some degree, different diameter tyres on my rear axle.
Is this likely to be a problem of any kind. For example, will it cause any appreciable load on the diff?
For info, I tow a 3 tonne van.
Many thanks in advance.
cheers, Dalb
Reply By: Ross M - Saturday, Mar 16, 2013 at 21:09
Saturday, Mar 16, 2013 at 21:09
Dalb (SA)
You don't give the tyre size so it is very hard to reply to something we can't work from.
A bit like asking an answer but not having any of the equation which makes the answer possible. AxB = X
If the tyre is new on one side and the old one is half worn ie, 805mm worn to 791mm then there is a 44mm circumferencial difference per revolution or around one turn difference every 50 or so revolutions.
The differential gears have then to make up the difference., as though you are continually turning one way. This wouldn't be happening at all if equal sized.
Not an ideal situation with nearly 2% more turns on one wheel.
If your vehicle has a centre differential and drives all 4 full time then the centre diff will be doing half of the drive difference front to back. Front drive shaft will be going about 1% slower than the rear one.
If your vehicle has an LSD I wouldn't be doing it as the LSD will be slipping the clutches full time.
If open diff then maybe ok but I would expect some shortening of the internal life that would otherwise be expected.
AnswerID:
506926
Follow Up By: desray (WA - Monday, Mar 18, 2013 at 22:14
Monday, Mar 18, 2013 at 22:14
Don't need the tyre size. He said the tyres are the same make and size, so whatever size they are makes no difference
FollowupID:
784243
Reply By: The Bantam - Monday, Mar 18, 2013 at 11:33
Monday, Mar 18, 2013 at 11:33
It would certainly be preferable to have tyres of equal wear on each axle...even from the point of view of getting the best economy out of ya tyres.
The vast majority of people don't rotate including the spare..and thus either have a barelly legal or brand new spare..and have an odd tyre....lots of low Km vehicles traded the spare tyre has never been out of the spare wheel carrier since it was put there at the factory
That is one reason I have 6 wheels for my vehicles.... I do a 6 wheel rotation.
As for how much difference it will make.
ON vehicles with single ( not dual wheels), each tyre runs and wears on its own and has absolutly no influence on the wear of the other tyres.
As far as any effect on the
suspension......serioulsy.....how.
As far as having any effect on the dif......OH please.......a vehicle is hardly ever going perfectly straight and the wheels are hardly ever tracking at identical speeds.
If you have a 6mm difference in tread depth.......on a 4wd tyre in the 800mm ish diameter that is less than a 1% difference.
Serioulsy less than 1%.
So its going to make less than 1% difference to the wear in the diff.
As far as legalities and insurance.....as long as the tyres are of the same, size, profile and construction, you can be perfectly legal with 4 different branded tyres in different states of wear.
If you want to get the best life out of this set of tyres...start rotating the tyres now.
Pick a tyre any tyre and replace it with the new one, then work that tyre around the vehicle, replacing each other tyre in turn.
you may want to do a front to back rotation along with.
It helps to number your rims so you can keep track..and draw a little diagrame in an excersize book.
cheers
AnswerID:
507035