I bought my first set of new wheels a couple weeks ago and the tires just aren't right. I bought a used set of 17x7.5 wheels with 205/40/17 Kumho AST tires from someone via ebay. I want to run these tires for a little while until temps are reliably above freezing. My stock (old) wheels have Bridgestone Potenza RE050A's with 10k miles (~50% treadwear), and they're 205/45/17. Never had any issues with the Potenzas, love the stickiness, but they're expensive, so I don't really want to buy a whole new set.

I've been having trouble getting the wheels to stop vibrating. I had them balanced twice (three times if you count the weight falling off on the highway) and I got an alignment at a good shop. A couple days after the car was aligned and wheels balanced, I drove 4h on the highway and the car pulled right and vibrated pretty bad between 60-80 mph (Let's just say I didn't drive slower than 60). On the way back, the car didn't pull as bad and the vibration was reduced, so I think it was related to bad treadwear from the previous owner.

Here are my questions: the 205/40's are stretched onto the wheels, and bumps are pretty harsh. Will I get a better ride quality if I mount the 205/45s? Are there risks associated with mounting used tires on a wider rim (7.0 vs 7.5")? Also, what's the ideal size tire for 17x7.5 rims? I'm not worried about rubbing, although I may install H-sport springs this summer (1" drop).

Thanks,
-Ben

 

I don't believe there is an ideal size, but Nitto makes a 225/40-17 tire that would be a good matchup with the OEM tire size. The 17 x7.5 rim size would be a perfect fit.

 

Do you have hub centric rings for these wheels? That may be causing your vibration problem. Also, if you had an alignment with used tires that will also cause your alignment to not be accurate because the wear on the used tires may not be even to give you a near to perfect alignment. It is ideal to have the car aligned once you install brand new tires so you can get it perfectly aligned.

The 205/45R17 size will improve the ride quality due to the taller sidewall, but the tire will still be a bit stretched on the wheels. I would recommend 215/45R17 on stock height, but if you do decide to lower it then go with 215/40R17 just to be safe.

Leo Barrios
leo@edgeracing.com
800-489-5353 x211
http://www.edgeracing.com

 

I have plastic hubcentric rings that appear to be in good condition.

Leo, thanks for the alignment insight, I didn't think about that. If I understand correctly, the tires may be worn unevenly, which would cause the car to pull, but also it would throw off the alignment if that were the case? Go Ebay...

 

You may also have a bent rim.....I'd check for that.

I just put 215x45x17 Nitto Neogens on 17x7 wheels and they are quite nice..

 

That is correct. The fact the tire could have been worn unevenly before you aligned it can cause the alignment to be off. Someone also mentioned that the wheel may be bent. That can also be a problem. I suggest you take them to a road force balancing machine. It will help pin point the problem as to what is causing the vibration. You can find one locally at this website: www.gsp9700.com.

Leo Barrios
leo@edgeracing.com
800-489-5353 x211
http://www.edgeracing.com