Running Different Tires

[GregW]

I have a 1993 525i and am planning on selling it before too long. My tires were bald so I had them replaced with some cheap used tires. The tire shop put on 2 Dunlop P215/60R15, 1 Goodyear P205/65R15 and 1 Yoko P205/65R15. I know it is preferable to run the same time, but didn't think this would be too big of a problem. Did I make a mistake or is it okay. I really don't take this care out on the highway, only around town.

Thanks

[Ross]

It certainly is a mishmash of crap, hope they didn't cost much. None of them are the correct size. Hopefully the tread patterns are similar and at least the sizes are the same on each axle.
It's not the end of the world but any buyer with half a brain will view that combination the same as your bald set and devalue the car for needing tires.

[Tiger]

bad mistake of not having pairs.

[632 Regal]

not necessarily,
bad mistake of not having pairs. stated he wanted to sell it in the not to distant future which gets the mis match game on. If they are same per axle so beit as long as they dont pull to one side or the other he is good. Any new buyer will see this if they are going to nickle dime him on the buy, but I dont think the seller here is asking 10k

[sal_park]

The 215 section tyres should be on the REAR axel and the 205s on the front

[Ross]

The 215 section tyres should be on the REAR axel and the 205s on the front
I'm curious to know why you figure this way is preferrable.

[sal_park]

I'm curious to know why you figure this way is preferrable.

Hi Ross,

It based my 5 which has the larger 255 section tyres at the rear and smaller 235 section tyres at the front. Also the is the only way round I've seen different width tyres setup on other cars (330 sport, M5 etc) and I suspect that this way round will cause less unexpected sliding over steer.


sal

[BigKriss]

i'd say larger tyres always on the rear also. but having different width tyres and different aspest ratios like the OP did does sound bodgy.

[RallyD]

i'd say larger tyres always on the rear also. but having different width tyres and different aspest ratios like the OP did does sound bodgy.

the different aspect ratio was used to keep the overall diameter of the tire as close as possible.
See for yourself: Tire Size Calculator (http://www.miata.net/garage/tirecalc.html)

[Ross]

Hi Sal,
Since both tire widths(they where all the same section,60) are slightly undersize for the car my logic would be that since the front does the vast majority of braking and all the steering to put as much rubber up front as possible. E34s are understeerers by nature.
EDIT
They are different aspect ratios, that tire store must have been tickled to unload that bunch.

[Tiger]

No one is going to buy the car just because of the tires... they are not only 3 different brands but also two wrong size tires.

[Russell]

No one is going to buy the car just because of the tires... they are not only 3 different brands but also two wrong size tires.

205x65x15 is the stock 525i tire size. Size is not an issue as circumference should be almost the same as a 225x60x15 which is the stock 535i tire size.

If i saw a car with missmatched tires (size and brand) I would not even consider it as I would suspect the owner did not maintain the vehicle properly. However, I am lusually ooking for preminum condition and not a fixer upper. Anyway, just my opinion.

[Tiger]

Exactly my point... would make buyer immediately suspicious that the owner doesn't take care of the car and may have alot of hidden problems that he is unloading onto them.

[Rick L]

Hey Ross,

I kind of lost you here. Reason why you would put narrow tires in front and wider tires in rear is for handling. Narrow tires in front gives you quicker response to steering. You might think this seems highly unlikely but by putting wide tires in front, you will lose road feel, lose responsiveness, and cause trim lining effect. And wider tires for the rear (for rear wheel drive cars only) for traction. Yes, E34 does understeer but you can compensate by making rear stiffer. This is done by adding more air to rear tires compare to front tires. And of course, if you have the ability to adjust suspension, you want to stiffen that too (struts and rear sway bar).



Hi Sal,
Since both tire widths(they where all the same section,60) are slightly undersize for the car my logic would be that since the front does the vast majority of braking and all the steering to put as much rubber up front as possible. E34s are understeerers by nature.
EDIT
They are different aspect ratios, that tire store must have been tickled to unload that bunch.

[healtoeit]

Did I make a mistake or is it okay.

I think it's a mistake, different tires handle different conditions (weather, speed) differently, so imo it's a safety issue. You say you just drive it around town, so the speed issue is mute but the weather issue is still there.

If I were coming to look at the car, I would take this as the sellers attitude toward fixing the car in general i.e. quick fixes, doesn't really care about the car, if the seller did not have service records, or if anything else was wrong I would walk.

I don't want this to come off as harsh and I can put myself in your shoes, just last week I had to replace a bubbled tire, but I had a second set to throw on right away.

[Rick L]

I totally agree...


I think it's a mistake, different tires handle different conditions (weather, speed) differently, so imo it's a safety issue. You say you just drive it around town, so the speed issue is mute but the weather issue is still there.

If I were coming to look at the car, I would take this as the sellers attitude toward fixing the car in general i.e. quick fixes, doesn't really care about the car, if the seller did not have service records, or if anything else was wrong I would walk.

I don't want this to come off as harsh and I can put myself in your shoes, just last week I had to replace a bubbled tire, but I had a second set to throw on right away.

[Ross]

Hey Ross,

I kind of lost you here. Reason why you would put narrow tires in front and wider tires in rear is for handling. Narrow tires in front gives you quicker response to steering. You might think this seems highly unlikely but by putting wide tires in front, you will lose road feel, lose responsiveness, and cause trim lining effect. And wider tires for the rear (for rear wheel drive cars only) for traction. Yes, E34 does understeer but you can compensate by making rear stiffer. This is done by adding more air to rear tires compare to front tires. And of course, if you have the ability to adjust suspension, you want to stiffen that too (struts and rear sway bar).
My understanding is that turn in is determined by tire stiffness, reducing footprint in front(or increasing in the rear) will worsen understeer.
Best thing this guy(OP)can do on the cheap is find two more to match the slightly undersize matching pair and throw the best of the rest to the trunk.

[Rick L]

I guess that depends on the driver... Race car drivers know that it is more important to have a good exit in a turn than coming hot beginning of the turn. Yes, most all cars will understeer when you make that initial turn but then you would need to GAVE GAS to bring that tail around to get good exit around the turn. This is where you need traction from the rear as the bias will shift and change, even on a car that understeers a lot. But who really drives like a race car driver... :p


My understanding is that turn in is determined by tire stiffness, reducing footprint in front(or increasing in the rear) will worsen understeer.
Best thing this guy(OP)can do on the cheap is find two more to match the slightly undersize matching pair and throw the best of the rest to the trunk.

[leicesterboy15]

I think it's a mistake, different tires handle different conditions (weather, speed) differently, so imo it's a safety issue. You say you just drive it around town, so the speed issue is mute but the weather issue is still there.

If I were coming to look at the car, I would take this as the sellers attitude toward fixing the car in general i.e. quick fixes, doesn't really care about the car, if the seller did not have service records, or if anything else was wrong I would walk.

I don't want this to come off as harsh and I can put myself in your shoes, just last week I had to replace a bubbled tire, but I had a second set to throw on right away.

I totally agree with this, if it was my car I wouldn't do it (not to say I haven't done it in my younger days on more mundane cars)

BUT - unless the buyer is car savvy this should not be a problem when it comes to selling. If they are looking for money off then mismatched tyres on one axle provides bargaining power for them if they spot it, if the buyer knows cars or is an enthusiast then as others have said they buyer will wonder what else has been scrimped on and will want to change the tyres also resulting in bargaining power. To the 'normal' punter (I know 'normal' is open to interpretation) they are more likely to look at tread depth and / or make of the tyre and as most people come under the 'normal' category you might be alright.

[Ferret]

I think it's a mistake, different tires handle different conditions (weather, speed) differently, so imo it's a safety issue. You say you just drive it around town, so the speed issue is mute but the weather issue is still there.

I also agree with this, under normal driving you wont notice a difference, it's in an emergency situation that a problem is going to occur.

As stated above the tyres behave differently - this means that if you *really* stand on the brakes, the different co-efficients of friction on the tyres means that close to lock-up point the tyres are going to be laying different amounts of force down on the road.

This in turn means that under emergency braking the car is going to be doing its best to yaw to one side, yes I know ABS will try and correct this, but if your foot reacts better than ABS as do most people who've been driving a while, you could end up in a sticky situation.

I would advise putting the mismatch on the back axel but you cant do that as the matched pair are wider.

I also agree though that if you're selling it, most people wont be that arsed about it as a lot of people view tyres as an annoying expense rather than something that will save your life!