RETTA TIRE SIZES

[Guest]

I'm getting ready to replace tires for the first time. I don't see a need for P215 tires since I do not drive in a sports manner (very seldom over 55). Has anyone else in the club changed tire sizes and experienced good or bad because of it. Or any other thoughts or suggestions. Joe Langford, member

[Guest EDBS0]

I have always upgraded to 225/60/15s<P>great great resourse is <A HREF="http://www.miata.net/garage/tirecalc.html" TARGET=_blank>http://www.miata.net/garage/tirecalc.html</A> <P>you can compare rolling diameters to keep your spedometer accurate.<P>I have seen Reattas with 17 inch rims but personally would stop at 16s<P>Robert

[tc11003]

I have an 89 and 2 weeks ago had Dunlop sp40's installed all around total with tax $300. Excellent price and tire , I recommend you get the standard tire size and go with a major brand tire at your local store.

[padgett]

First, the P - passenger<P> 215 - section width (formerly 215 was a "G") - little to do with performance, more related to the load rating.<P> 65 - profile <BR>Bigger for taller/narrower tire, smaller number for shorter/wider tread can range from 78 series (standard on most dull cars in the 1970s) to 40 (can tell if the cigarette butt you just ran over is plain or filter tip). <P> S/T/H/V - speed rating. Lowest is over 100 mph (is also found as the letter after the load rating - 95 for Reatta).<P> R - radial. Do not want B (Bias)<P> 15 - wheel diameter<BR>If you go to 225x60 from 215/65, the tire is about a half inch wider, is the same height, but really wants a wider rim (Reatta's is 15x6" - even in '88 should have been at least a 7" rim). <P>If planning on making the tire work, you want a rim close to the tread width see chart in URL below for recommended rim width for various sizes. IMNSHO you do not want to be on the minimum.<P>So for a stock Reatta with stock wheels, best stay with the stock size, is all you should mount on a 6" wheel.<P>Personally have Michelin X-Plus (branded X-One) since was after superior wet traction and have had excellent results on two other cars. Keep in mind that close to the same size, the tire construction is going to make more difference in ride, traction, and wear than the size. A cheap tire is going to be cheap in any size. <A HREF="http://tires.michelin-us.com/catalog/tires/x1.html" TARGET=_blank>http://tires.michelin-us.com/catalog/tires/x1.html</A> - plug

[Guest]

One other thing to look for. The Reatta was designed to use an "H",(130 mph), speed rated tire. While you may not use the speed rating of the tire, generally the higher the speed rating, the stiffer the sidewall and tread construction, to keep the tire flat at speed. It's not that a lower speed rating won't work, but it may have some effect on handling. By the way, the 225/60 size tire is almost 5mm smaller in rolling radius, which will cause the speedometer to read slightly higher. The 235/60 size is a much closer match, at just over 1mm larger radius, however the tire selection is very limited, at least in a speed rated tire. The stock 215/65 size tire is pretty common and you should be able to find a good tire at a decent price.

[padgett]

Think the "H" rating was more for glitz and the 125 mph limit in the PROM. The X-1 has a "T" rating (118 mph) that gives a softer ride (and the Reatta could use a softer ride).<P>In addition, the "H" and "V" rated tires often do not last as long.<P>I do not plan on entering the Reatta in any autocrosses so chose to maximise wet traction, ride, and life. Interchangability with two of our other cars also crossed my mind.

[tcams76]

2seater recheck your numbers.

[tcams76]

Padgett good choice in tire I just read the reviews at Tirerack. I will probably go with Yokohama DB's which are cheaper than your.

[Rawja]

I have installed Michelin Pilot XGT-V4 <BR>P-225-60 V15 tires on my '89. They made an incredible difference in the cars handling and ride. The larger size also looks better in my opinion.

[Guest EDBS0]

tcams76 <BR>I had the Yokohama DB's on my 89 before I sold it and recommend them highly 225/60/15s<P>Outsatanding ride quality, control and <B>QUIET!!</B><P>Robert

[Guest]

Okay, here goes: 225 x .60 = 135 mm, 215 x .65 = 139.75 mm. 235 x .60 = 141 mm. This the nominal height of the tire from the rim. Metric tire sizing is very easy to calculate. Section width times the aspect ratio yields the tire height, multiply by two for both sides. Either multiply the rim diameter by 25.4 to get mm, or divide the tire height by the same number to get inches and add to the rim diameter. Either way, it will give an accurate total tire height. In any case, the 225 tire is 4.7% wider than the 215 tire, but, a 60 series aspect ratio is 9.2% lower than the 65 series. I believe my numbers are accurate.

[tcams76]

Your numbers look good, but the tool <stole it> posted comes up with different figures.

[padgett]

Those are theoretical values but do not take in variations in tire design (have seen up to an inch variation in same size from different mfrs.) or load factors (can vary height somewhat with tire pressure).<P>The math is a good starting point but nearly all tire companies have web sites with charts listing their tire sizes for different lines.<P>Other thing to remember is that tires are flexible and they move under load. Always allow extra clearance if planning to push it hard.

[Guest]

Have Z-rated (149mph or whatever) Pirelli P6000s -- and wish they'd wear out! Very hard ride, which the convertible certainly doesn't need. I keep reading everyone's posts on tires, and take special note of the soft-riding ones for when replacement time comes.<P>Jerry

[Guest C.F.Massie]

Not planning to race this classic and I wanted a nice smooth yet sporting ride so I just stayed with the original OEM size tires. I have gone through Goodyear, Michelin, Dunlops and Goodrich tires and I like the Goodrich best. They give me the traction and handling characteristics I wanted and were quieter than the others. Also I like the tread pattern on the Radial T/A s, lots of grab for all season use.

[Guest]

'Tis true there may be some variation between brands, but it should not apply to the metric sizing. I won't belabor the point any further, but if you cannot count on the figures given to be accurate, how does one replace his tires with any sense that you will get it right? I'll get off the podium, as I am pretty anal when it comes to tires. I am a firm believer Michelin has it right when they say " the only piece of safety equipment that actually touches the road"

[padgett]

The section width and load rating is federal mandate so is pretty close. What I have seen the mfrs play around with is the profile (labeling a tire as a "60" when it measures as a "70"), tread width, and tread depth (my Michelins came with 12/32", many have 10-11, some less). Have see more of this in the "4 for $78" off-brands than name tires.

[tcams76]

I just ordered one 225x60 tire(dB) with a 16x7.5 wheel from Tirerack. If it fits I will order the other three. My original wheels were chromed, I guess they go in the closet.

[tcams76]

I just recieved the tire and wheel I ordered.<BR>On reading the Yokohama tire warranty I see that the warranty does not cover "Improper application of tire size and/or specification". So I am on my own...with the 225/60/16. But, maybe I will get lucky.

[ol' yeller]

When I purchased my '90 coupe in May, I had to drive it over 2,000 miles home to Seattle. It had a set of those 4 for $78 tires on it and they were one size too small. The ride was terrible. Part of it was that the struts were completely shot but the tires were a big contributing factor. Upon arrival in Seattle I replaced the struts, tires and as long as I was throwing money around I bought some aftermarket wheels too. I then had a 4 wheel alignment performed. I also replaced all the brake components and flushed the system but that, of course, had nothing to do with the ride. The tires I bought were made by Toyo tires and they are their top of the line Z800 Ultras. What a difference. I learned a long time ago that it doesn't pay to cut corners on tires. Buy the very best you can afford. As for size, I stuck with what the factory put on. That way you don't get into issues over speedometers and suspension wear. If you want to see how they look, my car is posted on the Members Cars section of the Reatta home page. My car is now in storage for the winter and I miss driving it a lot. C'mon spring! <P>Greg Powers

[Rattaboy]

tcams76, out of specification means putting a passenger tire on a truck or getting a tire way out of weight or speed raring for the vehicle you install it on. Changing the width or size up or down within reason will not affect the warranty. The Cimmaron tire probably is a no-no.

[padgett]

The key nowadays is the new load/speed rating of the tire. The 215x65x15 GT+4 that came on the Reatta is a 95H. This means you do not want anything with a lower rating (the "H" is a bit silly, IMNSHO, unless you plan driving over 100 mph, an "S" (112 mph) or "T" (118 mph) rated tire will probably be fine.)<P>"95" relates to the load per tire (approx 1500 lbs) since a FWD car in a corner may have most of the force concentrated on the outside front tire, I consider this a bit low but is considered OK. Would strongly advise not going to a tire with a lower rating such as a 215x60x15 which is only a 93.<P>Note the GT+4 has only a 240 wear rating. This is pretty low and is refected in my experience with them - they wear out fast. The Michelin X-1 for example has a wear rating of 700, almost three times that of the Goodyear.<P>Traction: look for A or AA (AA is recent and many older tires were graded under the old standard. Temperature: A or B. More important on the race track or with a heavy load or pulling a trailer than on a street car.<P>So whatever size you pick, just make sure the load rating is at least a "95" and the tire should be OK. Like anything else, you get what you pay for.

[Guest]

I'm amazed at the response to my question. It is just another case of this site being the best site on the internet. I think I know more about tires now than most dealers. There are too many responses to thank everone but "Thanks to All". <BR>I live in Henderson,NV so snow, ice, and rain is not a problem. I retreived msgs from past post (I print a lot of them) and decided on Michelin Pilot xgt h4 215-65-15 tires at Sam's ($94.74 for special order). I was more concerned with tire safety than I posted so that entered into my decision. I have had them 2 days and so far they ride great and handle better than I could imagine. I can be reached at "jclreatta@aol.com" if any question. Thanks again.

[tcams76]

I just finished testing the tire/wheel combo from tirerack. They were concerned with my combination, 225/60/16. I only purchased one the check the clearance. The source of any problem would be the front strut spring tower base. With my combo there is a 3/4 inch clearance to spare. I would not recommend a taller tire than this. I wanted to use this size to reduce the fender gap.<BR><See chart in above posts for the correct overall height>.

[tcams76]

Robert does your 225/60/15 close the fender gap any; your size seems the same as stock?

[Guest EDBS0]

The 215/65/15 has a diameter of 26 inches<BR>the 225/60/15 has a diameter of 25.6 inches<P>The answer to your question then is the 225/60/15 does not close the fender gap, it will actually increase it by an insignificant .4 inches. <P> It does put more rubber on the road, approximately.<BR> <A HREF="http://www.tirerack.com/tires/yokohama/yo_avsi.jsp" TARGET=_blank>close out sale</A>

[Guest]

What tire size should I run with a 17x7.5 rim?

[tcams76]

Thanks, they only have the stock 215/65/15 in stock. My stock wheels were chromed by prior owner. I may a have to move up to 16".<BR>$43.00 price is good however, do they ride hard?

[Guest]

is a 255 tire too wide?

[padgett]

Maybe a 255x35 on 9" rims but you need to be careful of the offset.

[Guest EDBS0]

245 might be tops. Have heard rumours about 255 it is going to be very tight if possible. Just might fit on one side and not the other. These cars were not built to tight tolerances. If rubs on outside fender lip you can roll it with a baseball bat. Been there and done that on other cars. If it rubs on the shock or shock mount toooo bad you are sunk. <P>The 255 is 40mm wider than the stock 215. Divide by 25.4 for number of inches = 1.6 inches wider ... and sidewall buldge? <P>Some manufactures only take the size as a suggestion. I have seen 255/45/17 reported as having the following...<BR>Side wall section and tread widths <BR>10 x 9.1<BR>10.1 x 9.1<BR>10 x 8.2<BR>9.9 X 8.2<BR>10.6 x 9.7<BR>10 x 8.1<BR>10 x 8.6<BR>10 x 9.1<BR>10.3 x 9.1<BR>10.3 x 9.7<P>While all the same size 255/45/17 some may fit, others may not. <P>I would order and have tires installed locally so you don't have to pay +$50 UPS to send them back. And if they have sidewall rub marks good a luck!

[Guest EDBS0]

Yes slightly harsher being in the VR Ultra High Speed category.<P>My preferred choice is the Yokohama AVS db I have had them and love them, quiet soft touring ride.<P>Have heard from several sources that Dunlop Sport SP 5000 are also an outstanding tire.<P>I would have gone for either of these after a bit more research but the $43 was just too attractive a price.<P><B>Bookmark </B>this resource! <A HREF="http://www.miata.net/garage/tirecalc.html" TARGET=_blank>http://www.miata.net/garage/tirecalc.html</A> <P>A 235/50/17 has a diameter of 26.3 inches which is within 1% and fully satisfactory.