2G Mismatched tires.

[spyderdrifter]

I'm just looking to find out how screwed I may be after doing this. So I had to replace my clutch recently, and during the time my car was down, my rear passenger tire somehow went flat. So after the clutch replacement I had another tire I had in storage put on. I usually have 225/55/16's on and the replacement is a 205/55/16. I have noticed that the 205 looks shorter in overall height than my 225's. However I need to get new tires anyway and don't want to waste money getting a new 225 that'll end up being worn more when I can afford to get the rest. I have decided not to drive my car unless absolutely necessary, like tonight. My wife needs her car in the morning before I get off work, so I drove my car to work, 5-6 miles distance tops, and haven't gone over about 40mph. How much damage could I be looking at if tonight's drive, and the drive home in the morning are the only times I drive it with this one mismatched tire? And spyder is AWD which is why I'm asking. If it were still fwd, I would already know answers.

 

[dgdsm]

I'm no sort of authority on tires, but the bottom line is that you're putting stress on the entire structural and suspension systems. But I can't imagine how 40mph for 5-6 miles in your scenario would make much of a difference. Try and imagine the stress that would go into a car by someone driving 40 miles on the freeway with a spare on one wheel. Anyways this is the gist of what a AAA tow-truck driver told me the one time I put a spare on my Spyder.

 

[ThunderChild]

It's not so much the suspension, but the awd components (rear diff, tcase, center diff and mostly, the viscous coupler).

The 205 is definitely shorter, 3.2% roughly in height and diameter. You will definitely put some heat into the VC when driving it at anything over parking lot speeds. Personally, I would limit driving as much as possible, it's hard to gauge the damage you're doing.

Quick and dirty way would be a VCE, but unless you have one or can sacrifice a spare VC, take out the t-case and D/S, youre kinda stuck. Continue at your own risk.

Does your car have a rear LSD?

 

[spyderdrifter]

What's a VCE? Eliminator to the VC? I do have LSD in the rear.

Here's another thought, since my mismatched tire is on the rear, would it do more harm to the rear diff, or the center diff?

 

[gofer]

What brand/moel are the 225/55/16 tires?

What brand/model is the 205/55/16 tire?

 

[spyderdrifter]

The 225's are a cheap brand called Starfires, and the 205 is a Uniroyal. No idea on model for either.

 

[turboglenn]

If anything, out the odd you're in the front where it's an open diff so you won't be stressing the rear LSD if so equipped. I'm interested in hearing any proven data aboutthis myself though

 

[spyderdrifter]

Since I need new tires in a month or two, I went and got a used tire of the proper size with 50% tread left so I don't have to worry. Still curious though for future knowledge.

 

[gofer]

The standard rule of tolerance is .25" from tire diameter to tire diameter, since you don't know the exact brand and model (just the size) the only way you can really know if you potentially damaged something is to physically measure them around the outside of the tire.

Again, should be within 0.25" (which is what the majority of our members gap their spark plugs too )


Some back story though, I did some research on those generic tire brand/sizes you provided above and IIRC the Uniroyals were ~ 24.9" and the Starfires were ~ 25.75". But, without knowing the exact models it's just me shotgunning the numbers. If they're accurate though, just hope the Uniroyal had 41psi of air in it and the Starfires were in the mid 20's so their diameters were a bit closer and nothing was damaged.

 

[spyderdrifter]

Wow, that's quite a difference in tire pressure. I did another matching size tire, but I think I did do some damage.

 

[boostdawd]

When I was younger and broke all my tires were different brand and occasional different sizes until I was able to afford some nice shoes. No ill effects for several years of driving on mismatched tires.

 

[boostdawd]

It's not so much the suspension, but the awd components (rear diff, tcase, center diff and mostly, the viscous coupler).

The 205 is definitely shorter, 3.2% roughly in height and diameter. You will definitely put some heat into the VC when driving it at anything over parking lot speeds. Personally, I would limit driving as much as possible, it's hard to gauge the damage you're doing.

Quick and dirty way would be a VCE, but unless you have one or can sacrifice a spare VC, take out the t-case and D/S, youre kinda stuck. Continue at your own risk.

Does your car have a rear LSD?

For give me if I'm incorrect but wouldn't 205 be the width? The 55 should be the height.

 

[spyderdrifter]

For give me if I'm incorrect but wouldn't 205 be the width? The 55 should be the height.

You are right.

 

[lasershark]

For give me if I'm incorrect but wouldn't 205 be the width? The 55 should be the height.

You are correct but to clearify a bit...
The 55 is a aspect ratio or a percentage, not a size. So a 205/55 and a 225/55 will have different sidewall heights. Essentially the 55 means it is 55% of the section width.

 

[boostdawd]

Ah I see. Thanks for the clarification!

 

[ThunderChild]

Thanks @lasershark, i didn't see the reply fast enough to clarify, haha.