Should I replace my rear tires ASAP? Help!

Is it safe to drive a car with new tires in front and old/very worn tires in the rear? Am I putting my life at risk, or can I let it slide for the next month till I can afford 2 more tires, or is my brother full of bull?

THE BACKSTORY (SIGH):

My car didn’t pass smog, I turn it in to get repaired, and the mechanic insists on replacing my front tires before he runs them on the dyno since he claims they’re too worn down and pose a hazard to him (possible blowout).

I couldn’t get out there to inspect for myself, or even pick out the tires I preferred. I tell the man: “Fine, fine, just fix my darn car NOW!”

I didn’t like not having control over brand/price, but I figured as long as the guy put on the correct traction/tread rated tires for my model car, all would be fine.

I tell my brother all this, and he asserts that I would need to immediately replace the two rear tires as well, since it’s dangerous to drive on tires with different tread/wear. (FWIW, my car is FWD)

Well, I’m out a couple hundred bucks from the smog repair as it is, and can’t really afford to replace the rear tires until January. Can I get away with driving on differently worn tires till then, or should I borrow the money somehow? Is there any validity to my brother’s claim, or is he exaggerating the situation (as he has a tendency to do :wink: )?

If I appear really ignorant about car maintenance by asking this question, please forgive! I’ve never learned, and that’s why I’m asking now…I drive a lot, why don’t our cars teach us by osmosis?!

Worn rear tires increase the risk of fishtailing during acceleration and turning, and cause loss of rear-end traction in turns. They will act to decrease your braking power, because they won’t grip the road as well, and there is an increased risk of blowout. In short, do get them replaced ASAP.

I would say you can, but that is purely anecdotal from my own experience. I went through a few years where I was replacing tires on my pickup truck one at a time due to inopportune punctures and whatnot. Often, all four tires would have varying levels of wear at any one time – though since all four were replaced within maybe the first 18 months, there were no balding tires to worry about.

However, there was definitely a downside. Handling definitely suffered. The truck handled very poorly in the rain at times. In wet weather, I’d have to drive very conservatively – 50 mph on the interstate, avoidance of lane changing whenever possible, etc. Also, regardless of weather, the truck always pulled left or right. If I could have afforded the cost of four tires, I’d have bought a complete set – believe me.

But I would say that if you are very careful with your driving, you can get by a little longer. Do be sure to have your back tires visually inspected – either by a knowledgable frend or by a tire-repair shop (it’s cheap or free around here) – to make sure they aren’t on the verge of blowing.

You probably got scammed. Unless the tire’s belt was showing, he didn’t need to replace anything. Did you see any tire deformation? Cracking? Anything?

You should have control over what tires you get (you should try for a matching set). Now that you have some (probably) no name / cheap brand on your car, getting a matching set might not be worth it.

But since it’s already too late, replacing the rear tires is optimal but, depending on tread depth, can wait a bit.

The danger isn’t fishtailing on acceleration, but on braking. Since your front tires are going to grip so much better than the rear, you might over steer in a turn. Just take it easy and get a tread measuring thing at Walmart to check the tread depth (1/16" is the bare minimal IIRC).

BTW, what tire did you end up with anyhow?

Huh? I don’t know what the law is like in Canada, but here, most (all?) states have restrictions on minimum tread depth and other regulations concerning tire condition. If you can see the belt, you’re already well past the point of minimum safety at least as far as the law is concerned.

It all really depends on the vehicle you have. If your car is 4 wheel or all wheel drive, all 4 tires should be changed at the same time. If your car is front wheel drive, you are okay for a while as long as the rear tires are legal. And from experince, it really doesn’t matter a whole lot with rear wheel drive unless you have independent rear suspension. I just put new rear tires on my 66 GTO but do not plan on replacing the front tires till next spring.

And I don’t think “fishtailing during acceleration and turning” is anything he’s gotta worry about either - worn tires or not. There’s no force acting at the back half of the car; it can’t do anything except follow the front. Unless there’s a half-ton of bowling balls rolling around loose in the trunk.

Tires, brakes, shocks, and rotors should all be replaced two at a time, on axle (front left and right - or - rear left and right). I’ve never heard of anyone saying that four need to be done (Not even w/ 4WD). If the tires are past their tread specs, than they should be replaced.

There are forces acting on the vehicle’s rear in a turn. But, I did miss the part of the OP where he said his vehicle was FWD.

If the rear tires are in acceptable condition, then there’s no significant harm in having them somewhat more worn than the fronts. I had my car like this for quite a while with no issues I could tell. If they are too worn down, they can pose a hazard, and should be changed.

Check your tires for wear, the Car Talk guys suggest having at least 3/32 of an inch of tread depth. That’s the distance from the edge of a penny to the top of Abe’s head. If you have significantly more than that, then you should be all set. If you’re in a snow heavy state, I’d think about replacing before you get to 3/32. Also look for uneven wear patterns, like the inside being more worn than the outside of the tire, that sort of thing. Those are signs of problems beyond just old tires.

You should also spend some time noodling around the car talk site, and reading your owners manual… They have good tips for things that are easy for the average person to check on their own, to prevent situations like this. Not knowing basic maintenance procedures is a sure way to have problems with your car.

Oh, I’m sure we have rules (I think it’s 1 or 2/32 of an inch) but does a smog tester check tires? The smog guy said it was a danger to blow outs which is BS. The test is run on a dyno that only runs to ~60 km/h (~35 mph). A blow out is not a concern unless there was some serious damage to the tire.

Unless of course your smog guys actually test tires as well (as in, they also do a safety check)?

New Hampshire is “Saf-C 3213.02 Tread Depth. A vehicle shall be rejected if the tread depth measured in a major tread groove nearest the center of the tire is less than 2/32 inch or 4/32 inch on the front axles of vehicles over 10,000 pounds gross vehicle weight.”

Why not “1/16 inch or 1/8 inch” ??

Anyhoo, anecdotally I know folks who put snows just on the front two tires, and that’s definitely a difference in tread and type of tire, with no trouble.

I think the smog guy was trying to sell you tires.

And I think you probably need them.

Take penny and insert it into the tread of the tire. The top of Lincolns head should not be visible. That’s about 1/16". It you can see the top of his head it’s way time to replace a tire. But I live in snow country, YMMV.

There is a saying - “This is where the rubber meets the road”. Think about it. Having a battery go dead is a pain. Having a window that won’t go down, or a radio that doesnt’ work is a pain. A flat tire is a pain.

But, a flat, or a tire that can’t do it’s job while you’re driving is much more than a pain. I think that good tires are one of, if not the most important part of vehicle safety.

Can you drive with new ones on the front and not the rear? Sure. Don’t do it for long though. Rear tire blow outs are worse than loosing a front tire.

Thanks so much for all the responses - I swear to Og I did a thorough search on Google before I posted here, and I still contend that this site is a more valuable source of information than 1,000 genuine hamster-run search engines.

badmana, I was also very concerned about being scammed. But I also knew going in that my tread was dangerously low on all 4 tires, and was planning on replacing them all in January when the cash flow was better. I ended up with Dayton Qaudra LTE’s, A/B 195 (so at least they’re the properly rated tire). And FWIW, the mechanic refused to run the smog diagnostic until he replaced the tires - yes, he was concerned that they might blow out on the dyno at ~35 mph! He either wanted to sell tires, or had a bad experience in the past. Whatever, I needed my car fixed ASAP, and the tires were needed anyhow. The timing was just inopportune.

Cheesesteak, I can definitely see more than the top of Abe’s head. My, what a handsome forhead he has! Fortunately, I reside in the sunny-and-bone-dry-wintry environs of Hell-A, and need not worry about heavy rains till February or so. I think I’ll make it to January. ::Crosses fingers and does dance to appease the weather gods::

(bolding mine)
Shame on you for mistaking my gender, Q.E.D. How could you forget the deep, lasting connection we made in post #163 of the Nerd Girl thread? I thought that meant something to you! ::Storms off in a teary huff::
:smiley:

:smack: I’m a stupid, stupid man.

Maybe some one has statistics on which one is more likely to cause an accident, but I’ve had one front tire blowout and two rear tires. The front tire blowout was much more difficult to control and get stopped safely than the rear blowouts…

You may be right. I shouldn’t have stated that rear wheel blowouts are worse than front. I don’t know where I picked that up, but I have heard it a number of times. It does seem contrary to common sense. It probably depends on if its a FWD, RWD, or AWD-4x4.