265/65/18 tires
02-14-19, 11:43 AM
#32
Pole Position
Your rims are the same but your tire diameter changed.
265/60/18 = 30.5”
265/65/18 = 31.5”
See: https://www.tacomaworld.com/tirecalc...0r18-265-65r18
VSC, ATRAC, and CRAWL works by comparing wheel speed differences among the wheels. So, if one wheel is smaller (spare tire for instance) than the other 3, then that creates speed differences with the smaller tire spinning faster than the others. VSC/ATRAC/CRAWL programming will think that the smaller faster spinning tire is “slipping” and will use brakes to slow down that “slipping” wheel. In the case of VSC/ATRAC, this can create instability on the highway as one tire is being braked for no reason. At low speeds, it is probably OK with VSC and ATRAC. But higher speeds (highway), it may become an issue.
With CRAWL, even at low speeds, it may affect. CRAWL is a super aggressive traction control that basically stops any spinning tire to push torque as fast as possible to the tire with traction...to create as close to an axle locker effect as possible. Because it is so sensitive to speed differences b/w the tires, this can create a situation where one tire will be braked and torque being sent to the other wheel (on same axle) unexpectedly, which then leads to your vehicle being forced to one side (like off a cliff! LOL).
Remember, rim size does NOT mean tire size.
As for donuts...all donuts have the SAME diameter as the OEM tires. It is just skinny. But diameter is same on all modern vehicles with stability and traction control. Tire width is NOT an issue with these electronic nannies. It is the DIAMETER of the whole tire that is important.
02-14-19, 11:52 AM
#33
Rookie
Thread Starter
Good information ... but how sensitive are these interventions with 1/2" difference in rolling radius ? ... and if this difference is "adjusted" by going (as an example) 5-psi down on the 265-65 and 5-psi up on the 265-60 tire(s) ? ... again, just to "get home" and not for distance ?
What if you cannot go to tire shop that same day? What if you have to drive a long way back that night? What if you want to continue on your trip instead of killing off your vacation?
Just buy a cheap *** spare in the same size as your other tires and put it down there. Of course, this does require that the size that you pick fit under your GX in the spare compartment, which is why i ask this question at the beginning.
I am 90% sure that i will go with 265/65/18 but i will only go to this size IF the spare tire compartment allows it.
Last edited by Madtiger; 02-14-19 at 11:56 AM.
02-14-19, 12:22 PM
#34
Pole Position
My question back to you is.......why risk it? Why guess it? Are you sure 5-psi is all you need?
What if you cannot go to tire shop that same day? What if you have to drive a long way back that night? What if you want to continue on your trip instead of killing off your vacation?
Just buy a cheap *** spare in the same size as your other tires and put it down there. Of course, this does require that the size that you pick fit under your GX in the spare compartment, which is why i ask this question at the beginning.
I am 90% sure that i will go with 265/65/18 but i will only go to this size IF the spare tire compartment allows it.
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Madtiger (02-14-19)
02-14-19, 12:26 PM
#35
Rookie
Thread Starter
02-14-19, 10:18 PM
#36
Madriger, do you have a trailer hitch? If so, which one?
when I installed the curt (with stock size tire) it took about an inch of usable spare tire size. There is still some room left for a slightly bigger tire (1” max!!).
if you don’t have a hitch you can probably upgrade the size with no issue.
This is may not be relevant, however, on my 100 series land cruiser I went from the stock 275/70R16 to a 275/65R18 (which is a full inch taller) with no issues. I think it’s worth a try on the GX.
when I installed the curt (with stock size tire) it took about an inch of usable spare tire size. There is still some room left for a slightly bigger tire (1” max!!).
if you don’t have a hitch you can probably upgrade the size with no issue.
This is may not be relevant, however, on my 100 series land cruiser I went from the stock 275/70R16 to a 275/65R18 (which is a full inch taller) with no issues. I think it’s worth a try on the GX.
02-15-19, 02:51 AM
#37
Rookie
Thread Starter
Madriger, do you have a trailer hitch? If so, which one?
when I installed the curt (with stock size tire) it took about an inch of usable spare tire size. There is still some room left for a slightly bigger tire (1” max!!).
if you don’t have a hitch you can probably upgrade the size with no issue.
This is may not be relevant, however, on my 100 series land cruiser I went from the stock 275/70R16 to a 275/65R18 (which is a full inch taller) with no issues. I think it’s worth a try on the GX.
02-15-19, 03:39 AM
#38
Super Moderator
Probably not an issue with sizes listed here but I think differing tire size issues are more related to potential damage to torsen CD. This seems to be an issue with many if not all full time mechanical AWD systems. Remember TPMS monitors spare as well
02-15-19, 05:23 AM
#39
Rookie
Thread Starter
Torsen center diff allows speed differences between front and rear axle; thus you can make turns around a corner......except when it’s locked. So minor speed differences should not do any damage to Torsen center diff (unless locked). For me, the main concern is how VSC/ATRAC/CRAWL reacts to speed differences between wheels on the SAME axle.
02-15-19, 06:21 AM
#40
Super Moderator
I should have clarified running a different size spare tire is not a good thing for an extended period.
perhaps damage issues only occur to viscous coupling setups in other automakers though?
perhaps damage issues only occur to viscous coupling setups in other automakers though?
Last edited by Acrad; 02-15-19 at 06:24 AM.
02-15-19, 06:31 AM
#41
Rookie
Thread Starter
I could be wrong...but Torsen center diff are gear-based...so, wear and tear is not an issue. Those other AWD systems (viscous coupling) are usually clutch-based...and yeah, i can see those clutches wearing out faster if you have different sized tires for long periods of time...running with a spare for a few days should be OK though.
02-15-19, 07:07 AM
#42
Pole Position
I could be wrong...but Torsen center diff are gear-based...so, wear and tear is not an issue. Those other AWD systems (viscous coupling) are usually clutch-based...and yeah, i can see those clutches wearing out faster if you have different sized tires for long periods of time...running with a spare for a few days should be OK though.
02-15-19, 08:11 AM
#44
Racer
I think the manufacturers built in some tolerance to compensate for minor variances. Similar to when the tires are worn out and you put in a brandnew spare.
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Craigyyy (06-17-19)