Tires, tires, tires

7006 messages, Last post on Oct 29, 2009 at 11:24 AM

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What is this discussion about? Tires, Wheels, Steering

Edmund's Feature Article: Tire Safety: Don't Ignore the Rubber on the Road

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#1030 of 7006 tire width by dudleyr Nov 20, 2001 (7:54 am)
It is true that at a given tire pressure and vehicle weight, you have the same area contact patch regardless of tire width. One thing to remember when stating that a wide contact patch is better than a long one. Cars are not only subject to lateral forces - cars also have to brake. So if you say you are gaining lateral traction you must admit that you are loosing it fore and aft. I don't think wider tires really help as much as people think. The more important factor is sidewall height. As you get a wider tire for your car you have to decrease sidewall height to maintain the same rolling diameter. The reduction in sidewall height keeps the tire from rolling over in corners, and is really what helps a car handle - and feel more precise. So your car may handle better with wider tires, but not just because of the width. To illustrate this a 195-50 tire would offer better handling than a 225-70 tire. Also note that a cheap and easy way to increase sidewall stiffness and reduce rollover is to increase your tire pressure. Your car will handle better with higher pressure, and you will get better gas mileage, and the tires will last longer. The ride will be rougher though, and if your tires are not well balanced you will feel more vibration in the steering wheel.
#1031 of 7006 Q by suvshopper4 Nov 20, 2001 (8:06 am)
dudleyr: "To illustrate this a 195-50 tire would offer better handling than a 225-70 tire." Not sure about this example. On the same vehicle, wouldn't the lower sidewall/aspect ratio (50) usually go with a higher treadwidth (not 195, but 225 in this example)? Maybe you don't mean these tires would be on the same vehicle, but in general. Dunno. Thanks for the confirmation on tire patch area remaining constant (and only the shape/configuration of the patch changing). Don't know if the article I read a few years back was in Autoweek or Road & Track (or elsewhere), but it made sense and stuck with me. Funny how a lot of people just figure 'wider is better' in all situations.
#1032 of 7006 suvshopper4 by dudleyr Nov 21, 2001 (6:51 am)
I was speaking in general terms, but you could use both tires on the same vehicle - the rim diameter would have to be different though. I don't have any charts in front of me, but it would be something like a 195/50R17 vs a 225/70R13. I used a very wide spread to illustrate - I don't think either of these extremes is actually made.
#1033 of 7006 tire vibration by erics6 Nov 21, 2001 (12:59 pm)
I replaced the Firestones on my 2000 Subaru Outback with Continental Touring tires. The tires vibrate at higher speeds. The vibration moves the steering wheel side to side and increases with the speed. Even at lower speeds you can see some movement. The tire dealer first tried rotating the tire on the rim 180 degrees and then replaced the tires, but the vibration is still there. The vibration seemed worse when the tires were first rotated. My dealer says that this is probably due to tire runout on this type of tire. Any other ideas?
#1034 of 7006 Tire Pressure... by chuasan Nov 21, 2001 (2:03 pm)
hi all, I am curious is it safe to increase tire pressure above manufacture recommendation? I am talking about 3-5 psi over. I always feel the recommended pressure leads to underperformed in cornering and acceleration. Do you think 3-5 psi will help this problem? Thank you Chris
#1035 of 7006 chuasan by bretfraz Nov 21, 2001 (6:31 pm)
Are we talking exceeding the car mfr spec? If so, then it's safe to experiment with tire pressures to get the performance you want. Just don't exceed the max tire pressure, of course. You have a Malibu, right? Well, my car is front wheel drive too. I run +2PSI in the fronts than the rears. My fronts are +7PSI over car mfr spec and +5PSI in the rear. But I am -5PSI from the max tire pressure. I've noticed that since over 50% of the weight is on the fronts that having a little more PSI helps with steering response without degrading the ride too much. I've been playing with the pressures for several months just to see if I can notice a difference. It takes at least 2PSI before I notice any real changes. I use a racing-type air press. gauge but I recommend those digital types (did you read that thread on tire gauges?). I've found a gas station that has a real air compressor instead of those $20 junkers you find nowadays. With both of these I can accurately play with the pressures. Have fun!!
#1036 of 7006 erics6 by bretfraz Nov 21, 2001 (6:37 pm)
Usually this needs the services of an experienced "tire guy" since there are several things that can cause this. A couple things I'd be curious about is are they using the proper wheel weight design, have the weights fallen off during your driving, is their wheel balancing machine operating properly, are they torquing the wheels too much causing a slight warp. Can they check the runout of the wheel and tire? I saw a balancing machine at SEMA show that had the ability to determine runout and what what causing it, wheel or tire. So the equipment is out there to figure out this one. You may need the services of a better equipped shop.
#1037 of 7006 Curbed Rear Tire by headers8 Nov 21, 2001 (10:22 pm)
I just got my first van (Toyota) and am not quite used to dirving one yet. Today while turning in a corner, my right rear wheel rubbed/swiped the curb (gutter). I am worried that I might have mis-aligned my wheel. Would anyone know, if I did (aside from getting symptoms on my tire later on or going for an expensive wheel alignment check?
#1039 of 7006 curbs by hpulley4 Nov 22, 2001 (4:25 am)
First, do a visual inspection. Does the rim seem to be in the right shape, or is it bent? Is the tire OK or is there a bulge in the sidewall? Is the tire holding pressure or losing it? If the rim is bent or the tire is bulging or leaking, then at a minimum you need a new rim and/or tire. If you aren't sure, go to your dealer or a tire shop. For free or the cheap price of a tire install and wheel balance ($10-20) most places will check out the tire and rim for you. Go to a place you trust, a place you've used before as some shady shops will replace anything you bring in as suspect; your Toyota service is probably a good place to go. Next, if the tire and rim check out fine or are replaced, drive it at low and freeway speeds. Does it feel the same as before or is there vibration or a pull? If you already got the wheel balanced and there are problems with the drive then you may need an alignment. If it all feels fine at this point, try to remember to check the tread on that tire after 5000km to make sure it is not wearing unevenly as uneven wear may show a slight alignment problem that you won't notice. You may be fine, you may not. I'd be more worried about the tire sidewall than the alignment. In my '95 Geo Metro I swiped the curb a few times and ended up with a bulging tire which needed replacement, but the rim and alignment were fine. On the other hand, my wife jumped a curb in our Saturn LW200 wagon recently and I was expecting the worst but it drove fine, looked OK and held air well; I had all inspected anyways (for free at my Saturn service shop) and all tested fine.