Sponsored

Got 17x10s and M&H drag radials 325 47 17, High speed sway and vibration normal? What psi?

Andy13186

Well-Known Member
Joined
Sep 19, 2018
Threads
106
Messages
2,445
Reaction score
1,432
Location
Florida
Vehicle(s)
2018 Mustang GT 10speed Aluminator Whippled
Hi I got some VMS 17x10 and M&H 325 45 17 drag radials on my mustang, they grip amazing but I get a lot of sway at high speeds and vibration at like 100+ mph. So far I tried 32 and 30 psi, is that proper for the street or should I go lower? The sway is kind of concerning and the vibration too especially at like 100-130 mph. My first set of drag radials so I dont know whats normal.

I am running the stock pp1 front wheels and tires with these on the back.

Any tips or advice would be appreciated.
Sponsored

 
OP
OP
Andy13186

Andy13186

Well-Known Member
Joined
Sep 19, 2018
Threads
106
Messages
2,445
Reaction score
1,432
Location
Florida
Vehicle(s)
2018 Mustang GT 10speed Aluminator Whippled
I lowered the tires from 31 to 26 and that seems to solved the vibration at high speeds mostly, and reduced the sway. Here is what the contact patch looks like at 26 psi, you can see the outside 1 inch of each tire is not in contact but I think thats due to camber and I dont know if thats avoidable. They grip amazing my max acceleration G forces went from .78 on the street to .92 on the street.

Yxmmfkm.jpg


Side pic


amAwmS6.jpg
 

aleccesarenriquez

Well-Known Member
Joined
Mar 19, 2018
Threads
38
Messages
458
Reaction score
186
Location
San Antonio, TX
First Name
Alec
Vehicle(s)
2017 GT PP
The tire width is probably a little too big for the wheel width. 325s are usually for 11" wide wheels. Most people run 305/45/17 on the 17x10s. Not sure if that would cause your issue or not but it's worth considering.

Also when you got the tires mounted, did you have them balanced? If it has weights on the rim, sounds like you did, so I wouldn't recommend taking them off unless you know for a fact they were balanced incorrectly. Take it to another shop to see if they are within spec.

Lastly, i'm not sure if M&H are different but 30-32 psi is pretty high for a drag radial from what I know. I usually keep my MT Et street SS around 22 psi. Usually higher psi should reduce sway so I doubt this is causing your issue, but it's something to keep in mind as you will wear out your tires prematurely if you keep it at that high of a tire pressure.
 
OP
OP
Andy13186

Andy13186

Well-Known Member
Joined
Sep 19, 2018
Threads
106
Messages
2,445
Reaction score
1,432
Location
Florida
Vehicle(s)
2018 Mustang GT 10speed Aluminator Whippled
The tire width is probably a little too big for the wheel width. 325s are usually for 11" wide wheels. Most people run 305/45/17 on the 17x10s. Not sure if that would cause your issue or not but it's worth considering.

Also when you got the tires mounted, did you have them balanced? If it has weights on the rim, sounds like you did, so I wouldn't recommend taking them off unless you know for a fact they were balanced incorrectly. Take it to another shop to see if they are within spec.

Lastly, i'm not sure if M&H are different but 30-32 psi is pretty high for a drag radial from what I know. I usually keep my MT Et street SS around 22 psi. Usually higher psi should reduce sway so I doubt this is causing your issue, but it's something to keep in mind as you will wear out your tires prematurely if you keep it at that high of a tire pressure.
Yes they were balanced but they were balanced at 30+ psi which is definitely too high, but they still moved on the rim. I dont know if they used tire lube when installing but there were no signs of that which I normally do have signs of with street tires. I know for a fact now that the tire is not in the same place on the rim as it was when they balanced it so the balance is totally invalid and possibly negatively affecting the setup. The sway is pretty much gone running 20-22 psi (cold-hot temps) but the vibration from misbalance is apparent above 80-90 mph. The grip is great though in a straight line , never felt anything like it but drag mode on these cars is so violent that apparently its moving the tire on the rim.
 

aleccesarenriquez

Well-Known Member
Joined
Mar 19, 2018
Threads
38
Messages
458
Reaction score
186
Location
San Antonio, TX
First Name
Alec
Vehicle(s)
2017 GT PP
Yes they were balanced but they were balanced at 30+ psi which is definitely too high, but they still moved on the rim. I dont know if they used tire lube when installing but there were no signs of that which I normally do have signs of with street tires. I know for a fact now that the tire is not in the same place on the rim as it was when they balanced it so the balance is totally invalid and possibly negatively affecting the setup. The sway is pretty much gone running 20-22 psi (cold-hot temps) but the vibration from misbalance is apparent above 80-90 mph. The grip is great though in a straight line , never felt anything like it but drag mode on these cars is so violent that apparently its moving the tire on the rim.
Yeah definitely get them checked out for a misbalance. See if the weight needs to be re-distributed. If they move again and go out of balance again, might have to remove the tires from the wheels to see what's going on.
 

Sponsored

Peedystablo82

Well-Known Member
Joined
Apr 1, 2018
Threads
26
Messages
269
Reaction score
35
Location
VA
First Name
David
Vehicle(s)
2017 mustang GT pp Paxton e85
I was about to try the same tire setup on my VMS rims, just like the ones you have. The et street rs will not hook under a 50 roll and definitely not on a dig on street prepped or unprepped with my power. (1000+ Whipple) Any more feedback on these??? Anyone else also?
 
OP
OP
Andy13186

Andy13186

Well-Known Member
Joined
Sep 19, 2018
Threads
106
Messages
2,445
Reaction score
1,432
Location
Florida
Vehicle(s)
2018 Mustang GT 10speed Aluminator Whippled
I lowered the PSI to 20 and they are great at that psi and they definitely hook well
 

Peedystablo82

Well-Known Member
Joined
Apr 1, 2018
Threads
26
Messages
269
Reaction score
35
Location
VA
First Name
David
Vehicle(s)
2017 mustang GT pp Paxton e85
What whp and torque are you around?
 
OP
OP
Andy13186

Andy13186

Well-Known Member
Joined
Sep 19, 2018
Threads
106
Messages
2,445
Reaction score
1,432
Location
Florida
Vehicle(s)
2018 Mustang GT 10speed Aluminator Whippled
What whp and torque are you around?
~480 they hook pretty well for me on the street though even without burnout and in cool weather, although my best 60 foot on the street is only like 1.87 with no burnout, I think on a good surface like a drag strip and with a burnout they would definitely hook from a dig.




They probably wont last long though, I think mine are atleast half done after about 1000-1500 miles on the street and 0 burnouts but about 50 1/8th mile runs and 15 1/4 miles
Sponsored

 
 




Top