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315/35x20 Users

5K views 45 replies 21 participants last post by  Auggie Doggie 
#1 ·
One my first road trip, heading to Cincinnati with these new rears. First thing I noticed when on the Interstate, it felt like a low tire or wind blowing sideways. Pressure was set at 35. Contacted my tech support in Springfield ( Oldfatguy). He suggested raising pressure. Up it to 40. Not much difference. Noticed ride a little harder which is understandable. Lower to 38. Ride is smooth but am feeling this little side sway. Any one have this experience when going to a wider lower profile tire. My tech support gave me all parameters for the Nitto Motivo. Thanks, Robert
 
#2 ·
Tires mix matched front and back some times do that. They have different sidewall squirm and flex. Had a Camaro many years ago and no money. Had nylon/ polyester tires on the front and got some used radials from a guy and put them on the back. Wow what a wild ride that was. All over the road until I got 2 more radials. Fixed the problem. Might be something similar you are experiencing. Good luck.
 
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#6 ·
I know you checked the lug nuts to be sure they are tight, 110 In. Lbs. I think.

Nick
Make that foot pounds. I'm putting my wheels back on this weekend. 110 ft lbs sounds right. I always have to check. Either the Caddy SRX or the SSR is at 100 ft lbs, but I can never remember which is which.

Mismatched tire sets with different sidewall flex will cause problems. The only other thing to check is to make sure your panhard bar is OK. It it's loose or broken, you will definitely have major swaying.

I have 315s on mine, and have never felt like it's loose on the highway.

I run mine at 30 lbs. front and rear.
 
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#7 ·
Robert, I do believe if you raise the pressure to 40-42 psi and try to just focus on the wollowing, not the harsh ride, it will be somewhat better. At least until after your trip and you can sort things out. Max on that tire is 50psi.
 
#8 ·
:banghead

Wow, In two successive posts, I see one that suggests 30PSI and the other talking about maybe 38-40 PSI.

Come on............:|

I would suggest one of those is LOW and the other is too HIGH. While as I recall, the door decal calls for 30 PSI frt/rear......many have had better results and handling by bumping that up by 5-6 PSI. Right now, I'm trying out 35 PSI.

As to any "wandering", I'm thinking back to a bad handling Vette I owned with those lousy "run flats" on it. Those tires were indeed part of the problem, but it turned out that rear tie rod ends were shot and fixing those made a big difference.

If in fact you're running four tires that (match) in terms of type/tread, I would look to other factors. You were either in a severe (cross wind) scenario and did not realize it as a factor or you have (non-tire and/or pressure) related problems and should focus on suspension parts.
 
#14 ·
Fronts: 275/40ZR19 Michelin Pilot Super Sport
Rears: 315/35ZR20 Michelin Pilot Super Sport

The fronts are taller and 1” wider than stock. They fill the wheel wells and look better IMO. The rears are significantly wider, as you know.

I run 35-37 lbs. Other than occasional trough wander from wide tires on some older worn asphalt roads, no issue. Pretty high winds today, zero issues rolling down the beltway.

I agree with OFG, I’d bet difference in tire sidewall stiffness, and grip(?), not air pressure. Most of us, self included, don’t put enough miles on their trucks to worry about wearing out the middle of the tires quicker with a couple extra lbs.

FWIW: I drive in the wet in Houston. I’ve had 3 vehicles with RSAs, and not a fan of them in the wet. I changed them out when it made sense (i.e. tread wear or badly checked with age). I’ve got two vehicles on wider Michelins, one and one on Continentals. The Continentals, surprised me and I really like them. If RSAs work for you (whoever reads this), that is cool.

- Robert
:silver:
 
#15 ·
Hey Robert, Just sitting here thinking about your tire problem, don't have any quick cures, but a couple guesses. It's either the tires themselves-this would be my first guess-in which case I would take them back when you get home, or a tracking problem. Since these are wider than the tires they replaced, is it possible that they are constantly trying to "climb" the walls of the troughs on the road surface, first one side then the other. They would be sticking out just enough past the track of the front tires to cause a little wallow on a worn road surface(this would be more noticeable on a asphalt surface that concrete). Don't know if that's it - just a thought - no charge!:nerd:
 
#16 ·
Hey Robert, Just sitting here thinking about your tire problem, don't have any quick cures, but a couple guesses. It's either the tires themselves-this would be my first guess-in which case I would take them back when you get home, or a tracking problem. Since these are wider than the tires they replaced, is it possible that they are constantly trying to "climb" the walls of the troughs on the road surface, first one side then the other. They would be sticking out just enough past the track of the front tires to cause a little wallow on a worn road surface(this would be more noticeable on a asphalt surface that concrete). Don't know if that's it - just a thought - no charge!/forum/images/SSRFanatic_2016/smilies/tango_face_glasses.png
Jim my same thoughts. I believe that the movement wasn't as noticable on concrete as blacktop. Will do some more research when I get back. Dam_ it's cold up here. @ Firetruck invites us up here than turns down the thermostat. Had a real good meal, Doris wasn't impressed with liquor selection. No BUSHWACKERS. See you in a couple.
 
#17 · (Edited)
I know what you are talking about. Years ago on my '99 30th Anniversary Trans Am it came with Good Year Eagle F1 GS tires, 275mm width all around. Those tires grabbed the pavement so hard you could let go of the wheel and it was as if a ghost was pulling the wheel left and right but staying in the lane. The tires would grab any lines in the pavement and just yank you around. It was the strangest feeling. The worst part was when you stopped hard...it felt like you would lose control. The grabbing intensified and nothing you could do would hold the wheel straight. Tire pressures didn't help it. I even took it back under warranty...it was normal behavior for that tire. When I changed to another tire the car never did it again.

BTW...I have Atturos on my truck, 275 in front and 315 in the rear. It has never exhibited anything like what is described above, even with those wide 275 front tires.
 
#20 · (Edited)
Robert
Great to see you again.
I forgot to look at your tires while in the parking lot this afternoon. Looking a pictures on the web it appears that these tires are asymmetrical not directional. Although its not real noticable. Look carefully at how they are mounted. They may have one inside out.
Just something to check somewhat easily that nobody has mentioned. Even though it may not say this side out on sidewall, compare the two rears.

Hope you stayed realativly warmed and enjoyed your visit.
 
#22 ·
Tires mounted correctly. Driving home on dry roads, found this feeling is only on certain roads. Dropped pressure and rides smooth. I know people are going to say that never happened to me. Well so be it. It is happening to me. Subject closed. Thanks for all your input.
 
#26 ·
OK Robert, let's cut out all BS and get to the real problem ... it's a weight distribution problem !!! Now PLEASE don't take this personal, but here is my solution. Doris is in the passenger seat at 90 lbs and you're in the drivers seat at 290. Then when you packed the cargo area for your cruise, you accidently put the the heavy luggage on your side of the cargo area, which put more weight on your side. Hey "Bro" you're an 18 wheeler truck driver and you of all people know about weight distribution. Your side of the SSR was hunkered down while Doris' side was barely touching the pavement. Have a safe trip to Utah.
 
#27 · (Edited)
There are a few reports of people having similar issues with sidewall flex with various models of Nittos. Plus, you lost just over 1/4 inch of sidewall compared to OEM, less structure to hold the road.

Probably just the nature of the beast that is amplified by having a mixed brand set of tires on since I would imagine that the Goodyears are pretty stiff up front.
 
#29 ·
Try a differnet set?

I have run two sets of Michelin Super Sports that are 315 35's. I run them about 2.2 which is 32 PSI. I get no wiggle out of either set.

I would check and see if the Nitto's sidewall stiffness is the problem. Running a different brand of tire on the front won change the stiffness. On brand may grip more etc.. If the rear tires are not mismatched then I don't think front to back would affect it except on an AWD.

Maybe someone in your area would let you try a different set of rears and see if you can tell the difference. I would ship you a set to try, but the freight is rather high.

Dave
 
#39 ·
Here is my conclusion. After reading Cozy dogs post about weight distribution I think I have it figured out.. I moved the battery from the inside frame to the outside frame. By doing this I threw off the geometric design of the vehicle which is putting more weight on the right tire and that's causing the squirm. So Mike you need to put a disclaimer in your battery relocation instructions.
 
#40 ·
Just add another battery to the other side. That way you will have one to use for a jumper when you leave the flashers on when parked.:surprise::surprise:
 
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