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Jerry
Jerry SuperDork
12/11/15 8:09 a.m.

At about 28k miles, autocross and Tail of the Dragon have taken it's toll on my Pirelli P Nero Zero or whatever they're called tires. I was planning to bite the bullet in Spring (before the Fiat Dragon trip in April.)

But on my 35 minute commute to work I thought "I wonder if I could get by with replacing the worst two tires with new exact same tires on the front, and the best remaining pair on the back?" Then I saw the Malibu weaving in and out of 4 lanes of traffic going 15-20mph faster than everyone else have the state trooper pull out behind him and I laughed and laughed...

Thoughts? Otherwise might just go with 4 Yokohama S-Drive's that are down to ~$85 each on Tire Rack.

¯\_(ツ)_/¯
¯\_(ツ)_/¯ Dork
12/11/15 8:11 a.m.

Sure, why not? I bought 2 pairs of rears for every one pair of fronts for my MR2s, it would have been pointless to replace all 4 every time.

captdownshift
captdownshift UltraDork
12/11/15 8:18 a.m.

You're not awd so go for it

KyAllroad
KyAllroad SuperDork
12/11/15 8:18 a.m.

Or even put the Yokahamas on the front and leave the better old pair on the back. They don't HAVE to match.

Robbie
Robbie SuperDork
12/11/15 8:30 a.m.

Generally, you will want the best two tires on the back (regardless of drivetrain layout) in street driving and wintery conditions.

It generally prevents the rear two tires from locking up under braking before the front two. (If the rear two lock, it's like trying to deal with an emergency maneuver while someone rips up on the handbrake).

Brett_Murphy
Brett_Murphy PowerDork
12/11/15 9:10 a.m.

Don't be afraid to troll Craigslist for tires that will fit your car, just be mindful of the manufacture date. You may be able to score a good deal.

iceracer
iceracer PowerDork
12/11/15 9:27 a.m.

On a FWD car it is best to put the new tires on the rear.

I found this out the hard way.

WildScotsRacing
WildScotsRacing Reader
12/11/15 9:59 a.m.
Robbie wrote: Generally, you will want the best two tires on the back (regardless of drivetrain layout) in street driving and wintery conditions. It generally prevents the rear two tires from locking up under braking before the front two. (If the rear two lock, it's like trying to deal with an emergency maneuver while someone rips up on the handbrake).

This. FWD cars get really squirelly under hard braking if the rear tires don't have similar (or better) bite to the fronts.

Jerry
Jerry SuperDork
12/11/15 10:20 a.m.
iceracer wrote: On a FWD car it is best to put the new tires on the rear. I found this out the hard way.

Really? I would have guessed the opposite. FWD, front tires do the steering, front wheels do the majority of the braking... I assumed the back tires were kind of along for the ride.

Robbie
Robbie SuperDork
12/11/15 10:28 a.m.
Jerry wrote:
iceracer wrote: On a FWD car it is best to put the new tires on the rear. I found this out the hard way.

Really? I would have guessed the opposite. FWD, front tires do the steering, front wheels do the majority of the braking... I assumed the back tires were kind of along for the ride.

The major problem is when braking hard (and on the street, you are only braking hard when the situation is already bad). Imagine first that the weight shift from normal to the front under braking is handled by the braking bias built into the car (which it is). Now, lets throw better tires on the front than the back. This means the front tires can take more brake pressure than the rears can before the front tires lock. That means the rear tires will lock up first when you are braking hard.

Rear wheels locked and fronts still rolling = very similar to handbrake dynamics.

Also, remember that both front and back tires need to be connected to the pavement to get a car to turn. The front wheels may be the ones that 'articulate', but both axles need traction to turn. I'll go back to the handbrake example, turning with more traction at the front than the rear mean oversteer.

The Hoff
The Hoff UltraDork
12/11/15 11:10 a.m.

All the major tire stores make it a policy to put the better tires in the rear. No mater if it's FWD, RWD, or AWD. The logic being that if the "old" tire fails it's easier to control understeer than oversteer. Seems to go against logic on a FWD vehicle being that the front wheels do all the accelerating, all the steering, and most of the braking.

Robbie
Robbie SuperDork
12/11/15 11:20 a.m.
The Hoff wrote: All the major tire stores make it a policy to put the better tires in the rear. No mater if it's FWD, RWD, or AWD. The logic being that if the "old" tire fails it's easier to control understeer than oversteer. Seems to go against logic on a FWD vehicle being that the front wheels do all the accelerating, all the steering, and most of the braking.

The fallacy of that logic is that while front wheels do all of the 'steering', they are only responsible for about half of the 'turning'.

Nick (LUCAS) Comstock
Nick (LUCAS) Comstock UltimaDork
12/11/15 11:30 a.m.

Understeer scares me. I have frequent nightmares that I'm driving along, try to negotiate a bend in the road, and nothing happens when I turn the wheel. I then wake up as I plummet off of a thousand foot cliff. I prefer oversteer. That way I can't see the ground approaching.

WildScotsRacing
WildScotsRacing Reader
12/11/15 11:43 a.m.
Nick (LUCAS) Comstock wrote: Understeer scares me. I have frequent nightmares that I'm driving along, try to negotiate a bend in the road, and nothing happens when I turn the wheel. I then wake up as I plummet off of a thousand foot cliff. I prefer oversteer. That way I can't see the ground approaching.

Understeer = you hit the wall with the front of the car. Oversteer = you hit the wall with the back of the car. Horsepower = how much speed you hit the wall. Torque = how much force you hit the wall with.

The Hoff
The Hoff UltraDork
12/11/15 11:59 a.m.
Robbie wrote:
The Hoff wrote: All the major tire stores make it a policy to put the better tires in the rear. No mater if it's FWD, RWD, or AWD. The logic being that if the "old" tire fails it's easier to control understeer than oversteer. Seems to go against logic on a FWD vehicle being that the front wheels do all the accelerating, all the steering, and most of the braking.

The fallacy of that logic is that while front wheels do all of the 'steering', they are only responsible for about half of the 'turning'.

I would call it stabilizing more than steering, but it does effect steering capability. Ever try tray sliding? Some serious fun with the fronts doing all the turning.

Jerry
Jerry SuperDork
12/11/15 12:46 p.m.

Quick scenario: raining and highway speeds. The main reason I know I need tires is because if I'm on the highway in a decent rain, let's just say it's invigorating...

I'm guessing the front tires are hydroplaning their asses off. Should I still put the good one's on the back?

Robbie
Robbie SuperDork
12/11/15 1:02 p.m.

In reply to Jerry:

yes.

  1. most drivers generally handle understeer way better (gut reaction to come off the power or go to brakes = weight shift to front wheels = less understeer).
  2. if you do get berked, your car's passive safety systems are much more effective head on than side on. Mostly a function of available 'crumple space'.

Edit: I should add that if you put the new tires on the back and move the better rear tires to the front, that should also fix your hydroplaning issue (unless your current rears are absolutely toast too).

Danny Shields
Danny Shields Reader
12/11/15 1:07 p.m.

In reply to Jerry:

If you are talking highway, rain, Dragon, I say bite the bullet, buy four new tires. She will drive like a new car, smoother, quieter and without sliding off into the trees.

Robbie
Robbie SuperDork
12/11/15 1:10 p.m.
The Hoff wrote:
Robbie wrote:
The Hoff wrote: All the major tire stores make it a policy to put the better tires in the rear. No mater if it's FWD, RWD, or AWD. The logic being that if the "old" tire fails it's easier to control understeer than oversteer. Seems to go against logic on a FWD vehicle being that the front wheels do all the accelerating, all the steering, and most of the braking.

The fallacy of that logic is that while front wheels do all of the 'steering', they are only responsible for about half of the 'turning'.

I would call it stabilizing more than steering, but it does effect steering capability. Ever try tray sliding? Some serious fun with the fronts doing all the turning.

Never specifically tray sliding, but I grew up in colorado in a FWD VW, and used to terrorize snowy parking lots quite frequently.

If you want to really feel what worse tires on the rear can do (and how quickly it can do it), go into an empty and snowy parking lot (hard-packed is best) with a FWD car and half set the parking brake (rear wheels should roll when you are going straight, but you should be able to feel the drag).

With the parking brake half set, get up to 25 mph, gently brake, and turn slightly.

WildScotsRacing
WildScotsRacing Reader
12/11/15 1:30 p.m.
Jerry wrote: Quick scenario: raining and highway speeds. The main reason I know I need tires is because if I'm on the highway in a decent rain, let's just say it's invigorating... I'm guessing the front tires are hydroplaning their asses off. Should I still put the good one's on the back?

A FWD car has greater hydroplaning resistance on the front in any case, due to increased normal force pushing down on them from the front-end weight bias. The objective is to better equalize the point at which front and rear begin to hydroplane, and placing the thinner treaded tires on the front will accomplish this, due the increased normal force improving the front. I have experienced this first hand (same set of 2 more worn and 2 less worn) : with the worn set in back in a steady rain, the rears were getting loose at 50 to 55 mph: reversed the tires the next day and got heavy rain a week later, I was able to run the same stretch of highway at 70 mph and it was rock steady.

Kenny_McCormic
Kenny_McCormic UltimaDork
12/11/15 1:44 p.m.
Jerry wrote: I assumed the back tires were kind of along for the ride.

They are, until they aren't.

Jerry
Jerry SuperDork
12/11/15 3:35 p.m.

Hm, much to consider, meditate on this I will. (Either going to inspect all 4 and rotate the best to the back/purchase 2 new ones, or just go S-Drive's all around.)

Thanks for all the advice.

Boost_Crazy
Boost_Crazy Reader
12/11/15 3:35 p.m.

If the car has stability control, be aware that it may not be happy if you mix and match tires. Same size tires are not the same size from different manufacturers. My Nissan Titan did not like it when I had to use a full tread correct size spare with three other well worn but otherwise matching tires. Mind you, there can be quite a big difference between a worn and full tread truck tire.

Jerry
Jerry SuperDork
12/17/15 6:14 a.m.

Update: just clicked "enter order" for 4 new 17" Yokohama S-Drives on Tirerack. Xmas bonus next week, decided it wasn't worth fooling around, and my local SCCA-member-owned shop gave me a good deal on the installation. ($546 mounted/balanced/aligned/TPMS)

iceracer
iceracer PowerDork
12/17/15 8:42 a.m.

I no longer have "two tire" choice problem. Due to regular rotation, all four wear evenly.

In the extreme. We require 4 snow/ice tires in our ice racing class. Two, whether front or rear would be unmanageable.

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