You drop your pressure to 45 for traction? Most tires, 45 is the maximum. I run the Nitto NT555Rs on the back of the Lightning at 25 for traction. 35 for average use.
Hi, Yes & No. Nitto555 G2’s are meant to be run at 50lbs, have dropped Rears even 5lbs is enough to help traction, but not affect drivability if I jump into twisties in the 100MPH range.
Traction is independent of surface area. It’s tire Composition, pressure,
suspension squat, weight transfer that helps launches.
Remember the guys in the 80’s with that awful “Airshock mania”? Cars were 8” too high, widest tires, and they just burned rubber & went nowhere, lmao!!
Still too many Cars with tires too wide, they float over the road & just...spin!
The GT’s are 285/30Zr20 in the rear, aspect ratio 30. Sidewalls are strong. Fronts are 19”.Yes. My bad, have run them at 35lbs for straight line 0-60’s, GT500...easier to grab my slicks.
Can’t go much below 42-45 with the Shelby, in the past spun the Rim 2X with the Nitto’s it ran (285’s, then-stock for a GT500) have the TPMS sensor & inner liner to contend with. If I’m going out with stoplight Shenanigans in mind & need traction, Slicks are a 10 minute hoopla.
Slicks I’ll drop to 18lbs, Rims have beadlock ‘s on the Hoosiers mounted on 15” Welds.
Ok, I’m thoroughly confused with your gear ratio’s. More..lost, actually..
I even dropped doing the math & used a plug in number program, and all was correct.. See if anything’s off in my interpretations...
Driving it manually, OD disabled, Torque Converter locked up in 3rd(2,000’r’s@25) & 4th(3,000R’s@45) with a 26” diameter rear tire....
255’s(25.4mm=1”, 255/25.4=10..A 10” Tire Width), a 30% aspect ratio on a 20” Rim (30x20=600, (6.0”) 20”Rim + 6”=26”), Ergo, a 10” Wide, 26” diameter Tire....I’m better at Diff.Calculus vs H.S. Math. lol!
SR55S 5 Spd Auto (4spd + OD) ratio’s..
1st, 3.250
2nd, 2.440
3rd, 1.550
4th 1.000 (As most every Auto/Manual is).
5th 0.750
Your info on RPM’s/MPH...
255/30/20 555’s in the rear, 26” Diameter, and in 4th (1:1 Ratio) it sits at 3000RPM’s at 45? That suggests gears are around 5.13’s.
In 3rd (1.55 Ratio) shifting manually you’re at 25mph with the RPM’s @ 2,000?
That lines up with 4.10’s...(?)
But, if you take the numbers & say you’re running 3,000RPM’s in 3rd @ 45MPH, that’s right for 3.31’s.
If you were running 2,000RPM’s in 4th @ 45, that lines up with 3.31’s.
Did you maybe mix them up?
With 45MPH @3,000R’s in 4th, that’s 3.31’s.
With 70MPH @ 3400R’s in 4th, that’s 3.73’s.
Did you get a 70, 80MPH reading in 4th, or OD yet? 2500R’s@70mph in OD in the Mustang is 3.73 territory.
It should be identical in your Lightning or Ranger or Mustang in the 1:1 Gear, 4th in your 5Speed Auto, a 4Speed Auto..3rd. If you’re running the same gear & rear Tire diameter.
OBKB!
Best!
John