I have an 05 mazda 6, with about 400 pounds of stereo equip in the trunk and 20 inch rims. The tires rub on the rear fenders. I put in mazda wagon springs and block spacers, this all helped out, but the tires still rub. I need to raise the car about 2-3 more inches and have stiffer springs......any suggestions?

 

If the tires rub, it's due to the backspacing/size of your wheel tire combination.

Stock tire/wheel size is 17x7 wheel, 60mm backspacing, 215/50R17 tires.

These tires below are close to equivalent in overall diameter/size....The first number is the width of the tire in mm, so you could get more clearance at the fender by running the 205 rather than the 225 (although the 225 will handle better as you have more grip surface)

225/30R20
215/30R20
205/35R20

http://www.discounttire.com/dtcs/infoTireMath.dos

Where do you rub? If it's just on the fender lip, you can roll the edge of the fender to gain a little more clearance. (If you don't know what I'm talking about, just go to a good body shop and ask them about it.)

I sure hope you upgraded your brakes along with these wheels. If you didn't, you probably increased your stopping distances from 60mph by at least 50 ft due to the increased mass of the 20" rims....Got any pics?

 

yes...its rubbing on the fender lip. I am going to role the fender lip. But I would still like to raise the rear of the car with heavier springs? do you know where I can get them?

 

Sounds like a custom application to me. I would think your best bet would be to contact Eibach or one of the other major manufacturers to inquire about a custom spring for your application. This is done for off-road applications all the time, so I would think they would also do street applications....Your probably looking at $300-400/pair for custom springs.....

What you should probably do is get a set of wheel scales (a set of 4 scales that can measure the weight at each corner) so that you can get an approximate weight distribution for the front/rear of the car. Sprung weight is what you really need to know (the total weight supported by the springs)

Springs are measured in terms of spring rate (lb/in)...I.E. a spring with a spring rate=100 lb/in means that when an 100 lb load is applied, the spring will compress 1 inch. You need to find out where your ride height needs to be (I assume you want it to ride a little lower than stock....take some measurements off a stock vehicle for comparison. Measure the length of the spring at ride height, and also at free length. (You can approximate the spring rate of your car by measuring the wheel well gap at ride height, then have a person of known weight get into the car directly above the rear tires and measure the wheel well gap (vertical) again.) Divide the weight of the person by the difference between the 2 measurements...this will get you close enough.

You'll need to provide the spring manufacturer with some basic measurements so that they understand the application....If you go with Eibach, maybe take a look at the ride height of a vehicle with their springs on it...If you like the look, tell them that is the baseline, but that you need to support the additional 400 lb over the rear wheels.

Good luck

 

and keep us updated on your progress!