I recently put on 2 new 205/45x16 Bridgestone Potenza RE711, which are V rated (made in Thailand, whereas the Bridgestone Australia website listed theirs as Z rated)with 2 almost new Bridgestone SO2 of similar size which came with a set of used Speedline ST1. The reason why I didn't get new SO2 was the price factor, as they cost almost twice that of the RE711, and I also intend to change back to 205/50x16, the recommended size, when these are worn. Now I have a few questions for the experts:

1. Will the difference in characteristics, e.g. compound, grip, speed ratings make this a dangerous combination?
2. If OK, which should be put to which axle, taking into account the Z and V ratings of the two. The tyre dealer recommended putting the SO2 at the back, being the higher rating, I thought the reverse should be the case.
3. I forgot to take a look at the wheels when they changed the tyres. Anyone with any idea what is the offset of 16" Speedline ST1?
Mine is a MY97 and the OEM 15" has 55 mm offset.

Thanks and regards.



[This message has been edited by lokokkee (edited 05 May 2001).]

 

The car will be unbalanced, possibly some vibration at high speeds and will lose on handling. You really shouldn't compromise on tyres with a car like the rex (I presume its a rex or similar). I too tend to think that the SO2's should go on the front, as you control the car from the steering front wheels, but then again I'm no expert. Anyone else like to add to this?

[This message has been edited by WREXY (edited 05 May 2001).]

 

WREXY, Can you please explain why the car will be unbalanced and prone to vibration when the tyres are new or almost new and they are matched on the same axle and dynamically balanced? Difference in grip and handling yes, but vibration? What can cause that?
Thanks.

 

Lokokkee, mixing tyres is not a good idea. Full stop. For example, people running PZeros made in UK with another one made in Italy often report irregular handling which is instantly fixed by changing the odd tyre. And that's with tyres of idental make, model and size.

Yours are not even the same size. 205/45 is smaller than 205/50, obviously. This will upset your speedo slightly (though hardly enough to get you in trouble) but your front and rear axles will be constantly turning at different rates. Not good. Again, the difference is slight and I don't know how your transmission would take to it, but if the answer is badly, those will have been very expensive tyres. Don't risk it.

Be sensible and get a proper matched set of SO2s and enjoy the car on the best rubber you can get.

Richard.

 

Lokokkee the vibration I would have thought would be caused due to the transmission controlling the 2 axles (well sort of,through centre diff). With 2 different sized tyres you'd be upsetting the tranny because of the wheels turning at different rates, which I feel could cause vibration, at fairly high speeds. I have to agree with Hoppy, not worth risking. Try and sell the RE711 and get 2 new S02's and you'll have peace of mind. Good luck with what ever you decide and happy motoring, regards, Wrexy

[This message has been edited by WREXY (edited 05 May 2001).]

[This message has been edited by WREXY (edited 05 May 2001).]

 

Sorry for causing some confusion there, the 4 tyres are all of the same size, i.e. 205/45x16. As the SO2 are practically brand new, it is a waste to discard them and change back to 205/50x16, hence the compromise with the RE711 in the interim. The problem of loading at the centre differential therefore does not arise.

I agree that even the same model made in different countries can be quite different, as the RE711 made in Thailand are V rated whereas the Australian ones are Z rated. But since my car can't possibly exceed 240 kph (not that I didn't try), the V rating of the Re711 should be adequate for my use and while it is nice to have SO2, the marginal safety factor may not be worth paying twice the price of the former.
Regards.