tire sizes

Hi everyone, I could not find it in a search, I seem to remember that Padgett has been using 225/60/15 tires on his Reattae. Is this a good idea for a 90 coupe without changing the speedometer accuracy much? Anybody else run a different size for grip or looks instead of the 215/65/15 stock size?

Thanks,

Richard

Assuming that your speedometer is presently correct, changing from 215 x 65 r 15 to 225 x 60 r 15 will change the speedometer 1.4% that is 8 tenths of one mph or it would read 59.2

Changing to 235 x 60 r 15 will only change it .4% but that size is harder to find.

Note there is a tire industry standard that should mean all brands would be equal in size but there will be some (diameter) difference between brands.

Does anybody have a recommendation for keeping the tire size what Buick put on the car or is there a benefit for changing to 235/60/15?

I realize Buick has smart engineers however I am wondering if their size choice may have been influenced by the bean counters. Anyone else have experience with different tire sizes on their Reatta?

Thanks everyone,

Richard.

I believe the engineers at Buick arrived at that size to deliver the best gas mileage as well as good winter traction in the northern states. However most of the guys that talk on the forum, if they change out tires have gone to 16" wheels. Having said that I run 225/6016. The general rule of thumb to keep your speedo accurate is if you increase the front number [width of tire] you should reduce the second number [sidewall height].

So having said that 225/60 16 is very close to the 215/65/15 stock size. [it is off by 2 MPH at 60 MPH.

I will check on the calculator I use and report back. [i use miata I believe]

Just got back. 215/60-16 is almost an exact match to the stock 215/65-15 set up.]

Some of the reasons (excuses) for changing tire size is to get more rubber on the road or to get a brand/size they like.

Go to www.powerdog.com

Enter your factory size (215x65r15 for everything but 1991 which was 215x60r16) that will give you the base size and other numbers.

then add the other sizes you are considering..... that will show you the difference between stock and the other sizes you choose.

I have strong opinions here. Both of my Reattae have 225x60 Michelins on 16x7 GM factory wheels. The stock wheels are only 6" wide which is abby-surd. The only reason to put anything bigger than a 215 on that narrow a rim would be to save the wheels from curb rash.

Thank you all for your time and advice. Since I don't see a set of 16 inch wheels falling into my possession soon I will stick with what Buick put on the car.

Richard.

Then a 215x65x15 is the right size. I don't think I have a set not on a car.

The original tire size is not so popular these days, but still a nice tire the P4 from Pirelli is available.

I have them and they ride and handle pretty well.

Michelin also sells a 215/65R15 in their 90,000mile Defender series. A really nice riding tire. I put a set of four on the Reatta back in Nov 13 and have been very pleased, but then Michelin has NEVER disappointed me over the many years that I have ridden on their product. Can't say the same for my adventures into other high end tires.

I was thinking of going with a set of raised white letter 215 65R/15's BF Goodrich or Cooper tires. Has anyone had any experience with these brands in this size tire? The TireRack reviews were pretty good on the Goodrich tires. I'll be driving them only spring, summer & fall. No winter.

John F.

I have no recent experience but BFGoodrich T/A have served me well in the past.

Last I looked, Michelin, BFG, and Uniroyal were the same company just high, medium, and low line.

Padgett,

Good to know.

John F.

Uniroyal was the worst tire I have ever owned by far. Best tires I've owned were Michlin, Cooper and Kelly tires.

I have Kelly tires on my Blazer now and they ride and drive extremity well. I get lots of miles out of my tires due to the tire store where I buy them rotates, balances and inspects them for punctures and nails every 5000 miles for free. They also inspect them for unusual wear and set you up for an alignment if needed. (not free)

FWIW: I highly recommend the Cooper CS4 touring tires . . . Very pleased with the handling and ride on the Reatta. I have also put these tires on a Cadillac STS and a Town & Country minivan. Last time I checked, Cooper was still manufacturing in the US for those of us who believe in supporting the "local" economy.