I have a Canadian LX which I think has the same size tires as the US base, 175/65/15. It's time to replace the delightfull Dunlops. It's hard to find the OEM size so I was wondering if 185/60/15 would work. I check with the Miata tire caculator and it says there would be a 1.1% increase in diameter. Any negatives with using the larger tires (MPG,) or should I look for the OEM size? Thanks for the help.

 

I think you had them backwards. you'll be running a tire that is .3" less in diameter which means your car will sit .15" lower than normal and will have more rotations per mile than it thinks it will have.

I'm running slightly larger for my snows with no problems. (185/65/15 instead of the stock 185/55/16 sport wheels)

down sides: with a smaller tire, Your warranty will be up a tad bit sooner than it should be. A taller tire will have more sidewall flex and be "mushier" in the corners.

195/60/15 puts your diameter at .2" taller or .6mph faster at 60mph (.5mph faster than a sport's oem tire size) and you have a nice selection of tires at tirerack starting at $55. They will have much better grip as they are a wider tire but only have .1" taller sidewall.

~SB

 

What he said lol...

Either a 185 60 15 or a 195 60 15 will work, the dimensions of the first respondee are right on. Smaller for more responsive drive, larger for comfort and fuel economy. Also spot-on with the Tirerack.com resource.

b

 

The owners manual says that the ABS and VSA systems depend on using the oem tire size. So what happens if you don't.... and how much variance is safe?

Specifically on page 278 of the 2011 Sport Owner's Manual, it says: "The ABS and VSA system work by comparing the speed of the wheels. When replacing tires, use the same size originally supplied with the vehicle. Tire size and construction can affect wheel speed and may cause the system to activate."

 

..........

 

So you are running the snowtires at 2% faster than oem (824 rev/mile vs 840 for the oem). Is a 2% error not a problem for the traction control system?

 

LOL






10 char on my nutsax

 

No TCS on the 09 sport without navi so I have no issues. The 2% should not be an issue at all as over the life of a tire, regular usage will wear off upwards of 1/4 of an inch worth of tread. In my case, I have an extra .2" of height because of my snow tire size so if I were to wear down .25" worth of tread (the expected wear on many tires before replacement is needed), I'll actually be running the OEM size when I have 20% worth of life left on the tires.

Things such as overinflating your tires or underinflated tires will have an affect on your ride height or overall diameter of the tire more than .2" and these won't impact the TCS system. (underinflated will prevent you from defeating the VSA system but the computer doesn't recalculate the VSA or TCS based upon knowing what the tire pressure of each tire is. - it just knows one or more tires is low)

Honda doesn't want you throwing oversized tires on the vehicle for safety reasons. Increasing by a few percent won't impact or impair safety in the least unless you are pushing your car to its absolute limit and then, wider tires will have better grip than the stock tires.

Just don't turn it into a monster truck.

~SB

 

Very good points. Thanks.
This was my next question. If the new, wider tires have a different pressure recommendation, will that set off the tire pressure sensor? I just have no idea how differences in recommended pressure compare to the sensitivity of the car's pressure measuring system.
No.... more like a very small minivan that goes very fast.

 

I believe that's relating more to the replacement of just 1 tire. You want all the tires to be the same size to keep the computer happy.

 

Is this correct? If so, what are the limits on what size tires I can use if I buy 4 at the same time?

 

Yes this is correct. The limits are basically whatever doesnt throw the speedo off too much and is an acceptable size for the wheel itself. (a 215 width on a 5.5" or 5" rim is probably not a good idea). Use Tirerack or the miata tire size calculator then read up here on others posts as to what rubs and what doesn't. My GS-R had 195/55/15" and I ran 205/50/15s when I went to dedicated summers and they were great. for the fit, i'd go with the 195/60/15 for all season. for summers, i'd go with aftermarket rims and tires.

~SB

 

And for all season on the sport, which 16" size would give me the most choices? I'm partial to Michelin and would like something like a Pilot Exalto A/S or a Hydroedge. I can see that with the 15" wheel the 195/60/15 offers lots of options but I'm not seeing as many choices with any of the 16" sizes.

 

205/50/16 for the sport(16 inch). 195/60/15 (15 inch) for the base are the most availabe, least expensive, closest to stock diameter sizes

 

205/50/16 is an almost exact match and lots of options.

~SB

 

thats what i did today! 205/50/16 bridgestone potenza RE760 sports

 

At the same size,price, and class as the RE760, I see the Continental ExtremeContact DWS. Did you compare the two? Wondering what you think of the Continental.