FLYT993

I will need to get new shoes pretty soon, and would like to know what are the widest tires (front and rear) I can use on my standard 17 cup wheels, I think they are 8in F and 9in R. Also, I have a C4 so I know my rears need to turn a little faster than my fronts...thoughts?

bill930p

285's should fit on the rears, might not look so good though

Mark in Baltimore

285's on a 9" wide 17? Really? I'm not an expert on tires, but that seems very wide for that rim.

FLYT993

Mark, maybe 275's or 265's then?

Don Plumley

I'm running 235/45 and 275/40

Martin S.

Your question, "what are the widest tires (front and rear) I can use on my standard 17 cup wheels, I think they are 8in F and 9in R."

If you have 8" front wheels, very rare wheels indeed, you can easily run a 235/45/17 tire paired up with a 275/40/17 tire. Don Plumley does this, I do this as do lots of folks. A great tire combination....available from Toyo in their RA-1 DOT race tire.

Why not a 235/40 tire with the 275/40/17 tire? Or if there were such a beast, a a 235/45/17 front with a 275/35/17 rear tire? It all comes down to your ABS computer that does not want to see a tire rolling radius delta, front to rear of greater than I believe 3%. Those with a manual can confirm this.

When you violate the rolling radius rule, your ABS will shut down...not a pleasant thing. I have a rolling radius EXCEL spread sheet I'll send you. PM me with your e-mail address if you want the spread sheet. On the sheet you simply plug in the tire width (235), the aspect in % (45), the wheel size (17") for fronts and rears and the rolling radius delta is calculated for you.

I mistakenly bought a pair of 234/40/17 front tires, whoops, I had to sell them to Bimmer racer.

Don Plumley

In addition to Martin's spreadsheet, here's an online calculator: http://www.1010tires.com/TireSizeCalculator.asp
http://www.miata.net/garage/tirecalc.html

Put in your front and rear and it will tell you the differences.

Edited for one that works...thanks Martin!

Martin S.

Here is what I got....


Not Found

The requested URL /garage/tirecalc.htm was not found on this server.
Apache/2.0.52 (Red Hat) Server at www.miata.net Port 80

Don Plumley

I cut the "l" from .html.

Try this: http://www.miata.net/garage/tirecalc.html

FLYT993

Thanks guys.....this is why this community is simply badass!

ssarchi

That means that the following "nearest to OEM" sizing for Michelin PS's is 3.3% out of size for the 17" wheels: 205/55ZR17 and 255/40ZR17

When I plug in the 205/50/17 along with the 255/40/17 to the calculator, I get a difference around .25%

Are people driving around with the 55 series front thereby disabling their ABS? If so, does this matter?

So much to learn, so little time....

Mark in Baltimore

Hi Dan,

As Don, Martin, et al have said, I think 275's are the biggest that most people here talk about using with a 9" wide, 17" rim. Maybe others have used a 285, but that's the tire size that I run with my 10" wide 18" Fikses. I have also run a 295 tire on the same rim, though.

Martin S.

Just to finalize re the above, "I think 275's are the biggest that most people here talk about using with a 9" wide, 17" rim."

275 is the largest size most tire mfg recommend be mounted on a 9" wheel. Also, it will be tough to find anything much wider for 17"...at least I have not seen it...but always ready to be wrong!

225 is the widest most tire mfg recommend be mounted on a 7" wheel, but I run 235 RA-1s, what is a mere 10mm. I have seen the Kumho 710 in a 245 mounted on a 7" wheel and the sidewall appeared vertical...so it appears that tire sizes, although labeled the same, may vary from mfg. to mfg.