How quickly will a bad alignment chew up tires?

I have a 91 miata. I purchased the FM 2.5 suspension kit and installed it last night.

I had planned to put the suspension on, get an alignment, then get new tires.

Unfortunately last week the safety inspection was up and the tires failed. Since I needed new tires I got a new set of dunlop direzza 2's. (Then re-read last months tire comparo in GRM about the superior BFGoodrich....) Tire rack delivered the tires in ONE day with standard shipping, I had them put on the 4th. I have never owned tires this soft before.

The problem is that the car is now about 150 miles from my house, I am at my fathers for the weekend (To celebrate his birthday, but I couldn't pass up his garage.) The car obviously has alignment changes from the lower suspension. I am worried about how severe it is, and how bad it could chew up my new tires.

Am I over stressing a few degrees of camber and a 150 mile trip? Or will my brand new tires have the insides chewed up making this trip. Can I over-inflate them to level the load?

I have a primitive bubble/magnet camber gauge, but no way to measure caster. I definitely lack the confidence to do an alignment myself, and there is no one I trust in this area.

Summary: will a 150 mile trip with increased camber from a lowered suspension destroy a new set of soft tires, or am I over stressing and should just get it aligned after the trip.

Pictures, just because.

I'd worry less about camber/caster, and try to get the toe as close to zero as you possibly can.

In my experience, a couple degrees of negative camber HELPS tire wear. What you need to worry about is toe - that is the real tire eater. Fortunately, you can set toe pretty easily with some string, some time, and some help. You should be able to google a number of how-tos.

Thanks guys, I didn't really think about toe changing with suspension drop, but that is easy enough to check and change.

150 miles isn't going to do diddly to your tires unless the toe makes your tires look as cross eyed as Uncle Joe.

Duke wrote: What you need to worry about is toe - that is the real tire eater. Fortunately, you can set toe pretty easily with some string, some time, and some help.

I do it with a tape measure, going from the center rib on either side of the tire about 4-5" up from the ground.

Not perfect, and not good enough for getting things to an exact figure, but it gets me reasonably close to zero, enough that tire wear isn't an issue.

I need more info on that van.

Yessir, toe is what eats up tires. Camber just moves it around. It's possible to do a very accurate alignment with string and a steel ruler.

And yes 150 miles with a lot of toe in or out will wreck a tire in short order!

Nothing to worry about. The only alignment change came from the drop, unless you're the rare beast that touched the alignment cams when doing the swap change. And that alignment change will mostly be a bit more camber, very little toe change at all.

Short version: nothing to worry about. Don't mess with anything, just drive home.

then take it to an alignment shop .. you should be fine

Caster doesn't make a difference, camber shouldn't make to much of a difference over 150mi., toe might be more noticeable. Toe out+ to much negative camber (or vice versa)= cupping but it shouldn't be toe bad over 150mi.

Keith Tanner wrote: Nothing to worry about. The only alignment change came from the drop, unless you're the rare beast that touched the alignment cams when doing the swap change. And that alignment change will mostly be a bit more camber, very little toe change at all. Short version: nothing to worry about. Don't mess with anything, just drive home.

The more I started looking up alignment for the miata, the more I wondered how a mild drop could affect toe significantly.

I measured 1/8" toe total front and rear, so there is too much. I would imagine it has been that way, the car has always tracked dead straight. My measurement is rudimentary, I figure 2/32" margin of error or so, but that still puts too much toe.

My cheap magnet bubble camber gauge esentially read zero, I'm thinking there is less than 1^ currently.

moparman76_69 wrote: I need more info on that van.

It is an 89 turbo. I bought it with a blown turbo. I rebuilt the engine, put a 2.4 DOHC head on it, swapped to an a523 trans (manual), rebuilt a hy-35w turbo, intercooled it, 2.0 cams, flex fuel injectors, walbro pump, leather seats, socketed PCM, 3bar sensor etc etc etc. This was my first vehicle I dumped money into after getting my first real job.

Unfortunately the turbo I rebuilt was not rebuilt properly. It also needs more tuning and de-bugging.

I keep loosing interest. The goal is to strip all the good parts, scrap the rusty shell and shelve the engine for a future project.