[Heesh]

I have a 2009 SRT8 and I just mounted Michelin Latitude Tour HP in 275/40/R20 front and 315/35/R20 rear on the stock wheels. Now when i am cruising at 40-45 mph I get a momentary shudder/vibration that you can feel even through the seat. It will go away and then repeat, at a regular interval. Seems to only happen at this speed.

My concern is that the new tires introduced a rotational difference enough for the differential to try to activate. But the diameter difference is in spec with the stock sizes. Diameter is Front/Rear 29.1/29.0 for the goodyears and 28.7/28.6 for the michelins, both .1 inch off.

Anyone else experience this when going different tire sizes then stock? My car has 19k miles on it ( i have only put on 2k, bought at 17k) and i doubt it has ever had the fluids changed. I know in my EVO it needs to be changed every 15k or else you will get some shuddering/groaning when turning. But in the SRT i don't get that when turning, ONLY when driving straight between 40-45mph. All other speeds feel great.

Any Ideas??? Should I be worried?

I have done searches but can't find anything definitive, some say its an issue others not.......

 

[TheBRICK]

Take the truck back to whoever installed the tires and have them check the balance. Usually though it'll happen at higher speeds but you never know. If it didn't do it before the tires, and did it after the tires, chances are it's the tires. I know Chris aka BlownWK ran those tires for a long time and never had any issues. They're still on his Jeep I believe. Good luck.

 

[Heesh]

Thanks for the reply, I will give that a shot. It doesn't bother me that much, just want to make sure i am not adversely affecting the car.

 

[TheBRICK]

No prob.... you never know. I've had weights not be stuck on good enough before and fly off pretty quickly so it could be a balance thing. Check to see if one tire has a BUNCH of weights on it. If so, they may need to rotate the tire on the rims so it will take less weights. Good luck.

 

[jim383]

When i put on my last set of gy runflats i told them let me no how much wt went on the tires and they said the left rear has 5oz so i said rotate the tire on the rim 180 degrees then rebalance it this time it took 2oz and all the other tires were min on wts. If it was a front tire i would do the same thing.