Tire size question

[sable996]

this is for 2006 Scion Tc, bought used last summer.
The tires on the vehicle are Yokohama H4S 215/40 R17 in good shape, but one tire got damaged and has to be replaced.
The std size Toyota recommends is 215/45 R17.
The question is if I can purchase 2 standard size tires 215/45 and install them together wit 2 215/40 (the same size on front).
This way it allows me to return to std size in time.

Thank you!

 

[BeanCounter]

You will lose the positive benefit from rotating your tires (i.e. right rear to left front, and so on). I'm sure you can run those though, but I don't know that I would. You'll just be increasing rolling mass for no good reason, in my mind.

Is there a reason other than the fact that Toyota recommends this size?

 

[Quattro Pete]

Does your car have traction/stability control? If so, the system may get thrown off by the two axles turning at different speeds.

 

[BeanCounter]

Originally Posted By: Quattro Pete
Does your car have traction/stability control? If so, the system may get thrown off by the two axles turning at different speeds.


Correct me if I am wrong but, other than the difference in a 215 tire size between manufacturers which is marginally small, only the width of his tire changed. This shouldn't effect his speed, but if you were talking about the aforementioned difference, I assume that slight of a change could throw a flag...

 

[Quattro Pete]

Originally Posted By: BeanCounter
Correct me if I am wrong but, other than the difference in a 215 tire size between manufacturers which is marginally small, only the width of his tire changed. This shouldn't effect his speed, but if you were talking about the aforementioned difference, I assume that slight of a change could throw a flag...

He mentioned two sizes: 215/40/17 and 215/45/17. So, he's not changing width, but he's changing height.

215/40/17 has a diameter of 23.8in and makes 848 revs/mile.
215/45/17 has a diameter of 24.6in and makes 819 revs/mile.

http://www.miata.net/garage/tirecalc.html

 

[CapriRacer]

Originally Posted By: sable996
this is for 2006 Scion Tc, bought used last summer.
The tires on the vehicle are Yokohama H4S 215/40 R17 in good shape, but one tire got damaged and has to be replaced.
The std size Toyota recommends is 215/45 R17.
The question is if I can purchase 2 standard size tires 215/45 and install them together wit 2 215/40 (the same size on front).
This way it allows me to return to std size in time.

Thank you!



First is that your current tires - 215/40R17 - have a smaller load carrying capacity than your original tires - 215/45R17. That increases the risk of a load related tire failure, which sometimes has tragic results.

So my recommendation would be to take the safest course of action and replace all 4 tires with the original tire size.

 

[BeanCounter]

Originally Posted By: Quattro Pete
Originally Posted By: BeanCounter
Correct me if I am wrong but, other than the difference in a 215 tire size between manufacturers which is marginally small, only the width of his tire changed. This shouldn't effect his speed, but if you were talking about the aforementioned difference, I assume that slight of a change could throw a flag...

He mentioned two sizes: 215/40/17 and 215/45/17. So, he's not changing width, but he's changing height.

215/40/17 has a diameter of 23.8in and makes 848 revs/mile.
215/45/17 has a diameter of 24.6in and makes 819 revs/mile.

http://www.miata.net/garage/tirecalc.html


Ah, thank you.
Dang metric measurements. Arghhh.

 

[sable996]

Thank you very much for all replies.
Looks like I'll have to go with the safest way and replace all 4.
Thanks again for your help.