Can't find the stock rear size tire 265/40 x 18 in the range of sizes in the new tires I'm looking at. In one brand/model the size is 275/35 x 18 Ran the numbers and the 265/40 is nominally 26.35" diameter, whereas the 275/35 runs nominally at 25.58" diameter. Does any one see a problem with the slightly less than 3% smaller diameter (other than a small speedo error)? This is my perfered choice (at the moment) Azenis RT-615. Even tho it's a "W" tire, it fills my needs. I have no plans at all of driving higher than 168 mph for ANY length of time so my driving will be well under the rated limits. JD
Jeff, I know this isn't exactly the answer to your question but, I have been using 295/35/18s on the rear of my 355C. Using the basic wheel/tire formula, the dia. is about the same as the factory reccomended size. Regards, Vern
Many "close" Stock: 265/40 x 18 = 26.35" Dia. Smaller: 295/35 x 18 = 26.13" Dia. 285/35 x 18 = 25.85" Dia. 275/35 x 18 = 25.58" Dia. Larger: 275/40 x 18 = 26.66" Dia. There's not really ANY selection of tires at the stock size. The alternatives are all within +/- 3% diameter. and there are a plethora of options in this range in both performance and price. I recall reading an article in one of the major auto rags a few years back that said 5% should be the greatest deviation if you change tire size. Has anyone used the 275/35 x 18 on the 355 back end? JD
Hi Jeff, I can not see a problem in using the 275 tire. The worst your going to see is your speedo being off slightly. I used a 295/30/18 on my car for a while which is quite a bit off from factory dimension and all I saw was a slight different reading on the speedo, no CEL or any adverse running problems. The reason I went to the 295 size was to get as close to the fac. dimensions and get a bit more width. Regards, Vern
Thanks for the tire recomendation. Already have done my research along those lines and have chosen an appropriate to my needs tire. I was asking my question in regards to size. Trying to keep brand preference out of the discusion as everyone has their favorite. Looking for tech info regarding size substitution for my application. JD
I would go with the larger width 35 series tires you mention. The car would look and drive awesome with that setup IMO. BT
I wrote the following a couple of years ago, hope this helps: ====== So, my recommendation is to stick with the stock size in front, 225/40-18, and move from the strock rear (265/40-18) to the larger 295/35-18, which will fit on your stock wheels just fine. You have several options for brands; I use Michelin Pilot Sport (not the Pilot A/S nor the Pilot Sport Cup), which others to whom I've recommended this have also liked. Alternatively, you can go with the Bridgestone S-03 Pole Position, for roughly the same price. Some go for the Pirelli, but I don't like them. BF Goodrich tires are not as good in the wet and/or too expensive. Again, stick with the Pilot Sport or go with the S-03s. If you want to save some money, look into Kumhos or Toyos. You can order Michelin Pilot Sports from Costco, and they'll install for free. Or order from www.tirerack.com, which MAY be cheaper. Tire Rack also sells the S-03. vty, --Dennis
I should add - I moved to the 295/35 a few years back (with the Michelins) and am very happy. Somewhat more grip in the rear, even with reduced camber on the street car (to make the tire last longer). vty, --Dennis
Increasing to 295's on the same size rim- won't that cause more of a visible overhang or bulging of the tire on the rim? I like the tire and rim to be as flush as possible.
Had to go with the 275/35 x 18. rears. Closest workable size in my Azenis ST-615 tire choice. 225/40 x 18's in the 615's for the fronts were available. JD
Hi Chris, It is fairly minor, the rim and tire match up fine(295/35).There was actually a slight benefit in that minor tire bulge by adding a little protection to the rim edge. When I used 295/30s there was a noticable difference but not bad. Regards, Vern
I use 225/40 18's in front and 275/35 18's on the rear and most of my drving is on the track. I use Toyo RA1's in case you are curious.
Be VERY VERY VERY careful when it comes to altering the 355 rear tires. I know if you use a smaller then rear tire size, the handling becomes very sensitive (at speed, the powersteering didn't help matters) and the stability of the car at speed is compromised greatly, as from a 355 owner who had a similar problem as you are having now (ie couldn't source a rear tire of the right size).
