Which tires wear out first, front or back?
- Thread starter b4black
- Start date
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SM105K
Streetlight Grand Prix Champ/ IG @fafomotorsports
The fronts should wear out first in theory. The fronts see the bulk of the power and weight. Remember even though the SHO is AWD, it technically is FWD bias with the ability to send power to the rears.
Tires wear because of weight and slip. The fronts see significantly more weight and more slip, so they will wear faster. Also the shoulders of the fronts see more wear than the shoulders of the rear due to higher cornering loads. The tires need to be rotated regularly to keep the tread depth in that 2/32" variance window.
You can make the rears wear faster if you activate the AWD and traction control more often, as every proper SHO owner should
I do! Which is why I'm asking. I get the theory (which is why I said I assume the fronts), but was hoping for a real world answer.
Maybe this is a better way.... If I drive the car hard and never rotate the tires, will they wear evenly with the AWD, or will the fronts or rears were out first.
SM105K
Streetlight Grand Prix Champ/ IG @fafomotorsports
I gave you the correct answer. If you don't rotate the tires the front will wear out faster.
luigisho
SHO Member
You got a real world answer. The power is biased to the front, the braking is biased to the front, the weight is biased to the front. You ever owned a fwd car before? Yeah yeah I know it says awd. it's power is biased to the front.
Sorry, I read "The fronts should wear out first in theory" as not real world.
Yes, I've had FWD and know they eat front tires. And my RWDs go through the rears first. Just wanted someone's experiance on these cars.
rwd cars wear out tires very heavily dependent on how one drives it. performance cars wear the rears faster because we all like to get on the gas, but the more sedate rwd sedan will wear the fronts first due to the weight bias toward the front, and the cornering loading on the front.
luigisho
SHO Member
That is everyone's experience who have had both driveline platforms. Sometimes you just don't know the age/ownership profile of the person posting, so it's hard to assume previous experience. You have had both rwd/fwd platforms and know how they wear. Curiosity is good but in this case you know enough to proceed accordingly. Trust your experience. You got this
skyshadow07
On a mission to get below 4000lbs
I have a question based on this topic but going deeper. So I owned an Evo 9 and tire size was supposedly VERY important. The Evo is always AWD. Apparently, if you had even 4/32 difference between the front and rear tires you could damage the transfer case (owners manual). I'm curious if this platform AWD is that sensitive. I don't have my manual so I can not check. I currently own an 18 Lexus NX AWD that is not sensitive to tire size variations.
6500rpm
Quality Always Shoots Straight
I try to cross rotate every other oil change, this is the first two readings-
ROTATION AND TIRE WEAR in 32nds (Start at 10/32”)
Oct 21st 2017 50,100 mi (gauged before rotation)
LF 7-7.5-8 RF 8-8-7.5
LR 9-10-8.5 RR 9-9-9
July 22, 2018 60,113 miles (gauged before rotation)
LF 7-7-7 RF 6-7-7
LR 6-8-8 RR 7-8-6
ROTATION AND TIRE WEAR in 32nds (Start at 10/32”)
Oct 21st 2017 50,100 mi (gauged before rotation)
LF 7-7.5-8 RF 8-8-7.5
LR 9-10-8.5 RR 9-9-9
July 22, 2018 60,113 miles (gauged before rotation)
LF 7-7-7 RF 6-7-7
LR 6-8-8 RR 7-8-6
afaik, all of the all wheel drive vehicles require tire tread within a 2/32" range to avoid transfer case / ptu issues.
your NX may not be sensitive to that because it is almost never actually in awd.
your NX may not be sensitive to that because it is almost never actually in awd.
skyshadow07
On a mission to get below 4000lbs
If the case is that it is not in AWD that often is why it does not need perfect sizes then wouldn't that be the same here? Everyone keeps saying the SHO is FWD with short spurts of AWD. My NX is tuned, water/meth, full intake, full downpipe exhaust and I never spin the front wheels. The SHO spun the fronts the first time I stepped on it. So it would seem the NX is more AWD than the SHO.
How is out AWD engaged? Is it a viscous clutch system? Is it all electronic off wheel speeds and slip?
How is out AWD engaged? Is it a viscous clutch system? Is it all electronic off wheel speeds and slip?
Johnbigdog
SHO Member
There is a sealed clutch pack attached to the pinion of the rear differential. There is a ball and ramp system that is engaged electronically to lock up and release the clutches to provide torque to the rear wheels. There is an AWD relay module that dirwclty controls this clutch. The pcm tells the relay module how to operate the Active Torque Coupeling Clutch (the clutch on the rear differential.)
The system is supposed to be "predictive" in that if the pcm thinks wheel spin is posible up front, it will engage the rear. I forget what the exact parameters are.
Here is a cut away if you like that stuff.
Attachments
skyshadow07
On a mission to get below 4000lbs
Love cutaways, that was an amazing explanation. Thank you
Johnbigdog
SHO Member
So "The Book" notes our car is primarily FWD, but under heavy acell, aggressive handling, or wheel slip is detected torque is provided to the rear wheels via the ATC clutch.
The PTU is a gear to gear trasfercase that is splined to the front differential.
SM105K
Streetlight Grand Prix Champ/ IG @fafomotorsports
IIRC the power transfer to the rear is limited by the clutch set up to only roughly 150 hp.
skyshadow07
On a mission to get below 4000lbs
That's the meat and potatoes this engineer loves.
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