New tire problems
 

Long story short, I needed some new tires for some base 18in rims. I put 275/40/18 on the rear and the stock size 225/50/18 on the front. I also realigned the car. Now the handling feels extremely "loose" even when I hit small bumps while driving straight. Has anyone had this problem and fixed it? I know the larger rears would probably have a small effect on handling but I didnt imagine it being this bad.

you need to break in the tires first.

if it still feels loose, then your tires are too wide for your wheels. you are getting too much squirm.

Even tirerack suggests this setup so I'm thinking there is another problem.

Those are some crazy *** sizes. Take it back to whoever installed/alignment/balanced and have em fix it. I took mine to Firestone one time and they had to re-do it about 3 times before I was ok with the outcome.

Good idea, i have only put about 150 miles on them. They are 9in rims so they are in the suggested range for the 275.

This may be obvious but did you check the lug nuts? You don't say...i have actually discovered loose lug nuts in the past.

Haha yes I have. I have had a shop leave the lugs loose before so I pretty much check them every time I get tire work done.

Oh Ok Good deal then yeah just do what she said and then if it rides like crap still take it back and have em look at it. I always get warranty they sell for alignment.

yah, with my driving, 150miles would be plenty, but see if you can do a quick launch or two to rid some of the outer rubber and try again. should stick if the 9" is within your tire's mountable range.

:tiphat: :tup: you never know. That is the extent of my help :tup:

says the lady that's making black ribbons on the asphalt... ;) :D

Your stagger is WAY too much. The wider your tires are, the more your car tracks to the road. 50mm difference (almost 2 full inches) is causing your rear end to track much more then your fronts. Ask anyone that goes wide on the front and how much the car tracks once its done. Basically your rears are tracking and your fronts are not or no where as noticeable. You need to fix your fronts or your rears. I'm running a 255/45/18 on front and a 275/40/18 on the rear with no issues. What brand tires did you buy?

Nitto 555 rears( not the dr's). Fronts are the stock advans but they are new. I thought that this could have been the problem but ive had cars with big drag tires with skinnies on the front that felt more stable.

Looking at it also, your rear tires are an XL (extra load) tire so the way they are supporting weight is also different. The tires are built differently so it could make them react differently comapared to a non XL tire.

Explanation from tire rack
"XL" vs. Standard load tires ... what should I do? - Miles of Smiles | Tire Rack

Using this tire calculator with your specs:

Tire Size Calculator

26.9" front and 26.7" rear = you have reverse stagger and thus you are going to be getting funky handling

You should be running 245-40-18 & 275-40-18 and your handling will improve greatly

also, cant believe it hasnt been mentioned yet, but different tire compounds = squirrelly ride. i had stock advan's in the front, and threw on some conti extreme's in the rear and the rear felt like it was gonna break lose at 50mph. put the same tires on the front and it was fine

Thanks for the input guys.

There's no reason in the world to run such a stagger setup from front to rear. The fronts should be brought up to 245s. I agree with the above about it being a tracking issue. I run 285s and 255s, 19x10.5/9.5 so the tires grab grooves on the road all day. That may be what you're experiencing.

Excellent point

:iagree:

that's because most car guys dont do this to begin with. :icon17: