tyres 50 or 60 profile?

[assynt road]

Hi guys, am I right in thinking my 350i should have 60 profile tyres all round? At the moment I've got 60's up front but 50's on the rear. Have got to replace the rears so am wondering if to do a straight replacement with 50 profile toyo's or go for some 6o's perhaps Avon zz3. What size and makes are most popular?
All feedback appriciated!
Steve.

[400SE Dave]

To keep the rolling radius the same I assume you have wider tyres on the rear than you do on the front then???

400SE's have 225/50/15, I think the standard 350i's had 205/60/15.

I guess you have better traction with the wider tyre as there is more rubber on the road but I think there is more choice of tyre if you go for 60 profile tyres.

[vampire222]

205/60/15 is standard all around, so the rears too. I wouldn't do lower profile tires in the back than in the front tbh.

[assynt road]

400SE Dave said:

To keep the rolling radius the same I assume you have wider tyres on the rear than you do on the front then???

400SE's have 225/50/15, I think the standard 350i's had 205/60/15.

I guess you have better traction with the wider tyre as there is more rubber on the road but I think there is more choice of tyre if you go for 60 profile tyres.

Yes, I should have mentioned that, Rears are 225/50/15, fronts are 205/60/15. Does the extra width increase the rolling diameter?
Was wondering if the lesser? diameter, would effect the acuracy of the speedo, i'm guessing it takes the speed off the driveshaft?
I'm just trying to understand why i've got 2 different profile heights on the car?
The extra width of the rears is down to trying to tame the 4.6 motor!
Cheers, Steve.

[assynt road]

vampire222 said:

205/60/15 is standard all around, so the rears too. I wouldn't do lower profile tires in the back than in the front tbh.

Yep, that was my thoughts too, but saying that, the car handles lovely even tho its running odd profiles at the mo!

[400SE Dave]

assynt road said:

Yes, I should have mentioned that, Rears are 225/50/15, fronts are 205/60/15. Does the extra width increase the rolling diameter?
Was wondering if the lesser? diameter, would effect the acuracy of the speedo, i'm guessing it takes the speed off the driveshaft?
I'm just trying to understand why i've got 2 different profile heights on the car?
The extra width of the rears is down to trying to tame the 4.6 motor!
Cheers, Steve.

The lower profile compensates the extra width. Using the guide from an Alloy Wheel website (hope this link works http://www.alloywheels.com/Tyre_Calculator you can re-enter your tyre info)it says that with the wider tyre on a 50 profile you will be doing 67.55 when your speedo says 70 so at least you are on the safe side!!

At some point someone has decided that wider rubber was the way forward

[assynt road]

400SE Dave said:

The lower profile compensates the extra width. Using the guide from an Alloy Wheel website (hope this link works http://www.alloywheels.com/Tyre_Calculator you can re-enter your tyre info)it says that with the wider tyre on a 50 profile you will be doing 67.55 when your speedo says 70 so at least you are on the safe side!!

At some point someone has decided that wider rubber was the way forward

Thanks for your answers Dave, i now understand! I shall go for a straight replacement i think. Much the best policy, when your as clever as i am!;)

Edited by assynt road on Thursday 19th January 21:31

[pjac67]

assynt road said:

Thanks for your answers Dave, i now understand! I shall go for a straight replacement i think. Much the best policy, when your as clever as i am!;)

Edited by assynt road on Thursday 19th January 21:31

Good choice - if it aint broke, don't fix it.... if car handles well in all conditions - which it does
FYI tyres were fitted prior to 4.6 but previous engine had an aftermarket cam..

Regards, Paul.