Front tyres worn on inside

soup dragon · 03-12-2005, 03:06 PM

Checking over my car car today-noticed the right front tyre was noticably more worn on the inside than the outside (across 1/2 the width of the tyre)
The left tyre is worn similar but not as bad as the right one.
the car is an 88 targa rhd with stock 6x16 205/55 dunlops at the front.
i think i read somewhere that this is common?

Jack Olsen · 03:39 PM

It depends on your suspension settings. Of the three adjustments to wheel position (camber, caster and toe), running lots of negative camber is probably the most likely reason your insides wear out first. (Although toe angle can also cause odd tire wear.)

Camber is the angle of the wheel relative to a straight up and down line. Negative camber means the wheels lean in, with the tops of the tires closer to the center of the car than the part that's in contact with the ground.

A picture is worth a thousand words:

See how the wheels 'lean in?'

The reason you do this is so that the wheels are closer to perpendicular to the pavement when you need it the most -- in hard turns. As the chassis rolls under lateral loads, the outside wheel (the one that's doing all the gripping) will be closer to straight up and down. If you started with no negative camber, your outside wheels would be rolling over themselves in hard turns. The contact patch wouldn't be flat.

So, camber helps the car corner, but leads to early wear on the insides of the tires if you drive in a straight line most of the time.

A suspension shop can get your settings to a point where your tire wear will become more even, based on they type of driving you're doing.

masraum · 03-12-2005, 04:26 PM

My '88 wore the left side worse than the right, but that was because the places where I had the most fun involved right hand corners. Get the alignment done. You probably need a bit less toe in and camber. If it's just camber you can get sticky tires and start driving more aggressively or go to autoX and/or DE's. The tires that came on my car wore lopsided. When they wore out I got good street tires and was taking corners hard and the next 2 sets wore evenly.

soup dragon · 03-13-2005, 12:09 AM

Thanks for the input guys,i will get them to check the camber setting when they fit the new tyres.
Cool car jack - youve got some wide rubber on there-guess a bit spendy when they need replacing

GrantA · GrantA's Garage

Hi Soup Dragon,

Here is a "shop" that can do all the alignment you will need to get your wheels pointing in the right direction http://www.protyre.co.uk/ not sure if there is one near you but Protyre is well recommended here in the south west. (I have no association with Protyre other than as a customer.)

If you have that black pitch like stuff on the top of the front suspension mounts you will need to dig that out before you present your car for alignment. Also it will save time at the "shop" if the tie rod adjusting nuts are free to move. Good luck.

Grant

___________________________________
1978 911 SC Targa

soup dragon · 03-13-2005, 04:39 AM

Cheers Grant,gonna do a bit of asking around the local area,weve got loads of tyre fitting places (they carnt all be like Krap-fit!)

masraum · 03-13-2005, 06:22 AM

Don't forget the toe in, with a little camber, but too much toe in you'll wear the insides prematurely.

3.2 CAB · 03-13-2005, 06:38 AM

I have found that usually it is simply toe adjustment is off, seems it is the easiest to get out of wack.

Wil Ferch · 03-13-2005, 12:56 PM

Steve:
If there is too much toe-in...wouldn't the *outside* edge of the tire wear out first?? ( as opposed to the inside)

Do a search..I asked the same question, I had too much wear on the right front tire on the inside edge..I was running too much negative camber. For me, the inside 1 inch of width was wearing fast. I adjusted camber ( 1mm at top nut = 0.1 degree).....by moving 3mm....and all is fine. If you're wearing the inside "half" of the 205 tire...maybe you need to adjust only 1mm.

Wil

pwd72s · 03-13-2005, 05:05 PM

A factory technical specifications booklet, or a shop manual should give you caster & camber specs for your model car. For street use, with occasional sport driving, this is a good starting point. Oh, I forgot...on an early 911 at least you want to "give her a little toe". In other words, you want your front wheels pointed inward a bit, at rest, to offset their natural inclination to "toe out" as speeds increase. Me? I'm a wimp...I just took my car to Mr. Gamroth, up in Tualatin, Oregon, and beg him to make my car work well for frisky street driving. He did exactly that. There should be somebody with similar skills somewhere over there...Alignment can be an art form...