peet

Yea, this may be very basic and I think I know the answer, but why go to a 275 tire on the rear (18") versus a 255? The 275 if 6 lbs heavier so logic dictates it actually costs performance, but also logic says that there's now an additional six or so square inches of contact patch so the car hooks up better.

Is there more to this than meets they eye? At 5500 I need to dump my stocker rears and am trying to decide 255 or 275.

Thanks all!

Even Money

Unless you have aftermarket wheels or modded ECU with more power, I'd just go with 255s. 275 on a 9" rim is almost too wide.., 265 would be OK.

SebringSilver

265s are the best fit for the rear wheels. I've made this switch and have observed marked improvements in handling characteristics.

peet

Thanks for the suggestion - any reason why though? Is it the contact patch v weight issue as I suspect? What's the physics play here?

Even Money

What do the 265s do to the speedo, or is the speedo calculated off the front wheels??

peet

I doubt it does anything - it's 10mm wider and at 35 that's 3.5 mm taller or bigger diameter. Original question stands though - anyone?

GBlansten

X infinity

Just switched to 265/35/18s for the rears last week. I get so much less tire spin now. Even pulling out of my neighborhood which is an uphill right turn I'd get some inside tire spin. Now it is much less. I'm hoping the rears last longer now and I like the added traction.

GBlansten

1.1 percent difference. The 265 will read one mph slower.

If the real speed is 60 mph then the odometer on the 265 shod car will read 59.3

Just add 1 mph to what the odometer says when driving the 265 car.

Even Money

I had seen somewhere posted in this forum that you could input the new tire size in the nav computer and it would correct for that?? If not, then my theory is that since most car manufacturers might have the speedo read slightly higher than actual, a slightly larger diameter tire would correct for that and give you a true indication of speed(since your RPMs will stay the same for a given speed).

Savoy6

yeah i just changed to 275 too wide. changes the handling too much. going to 245 front 265 rear on the next set.

GBlansten

The speedo is probably a bit fast when the rears are nearly worn while the fronts are almost new on our cars.

GBlansten

I replaced the fronts with the stock size 235/40/18. How come you plan to boost up the front size?

Savoy6

straight line 275's are fine. but can barely make it around a turn at the posted limit without the traction control going off and quick lane changes especially under power almost set the car into a tank slapper. not having fun at all on them right now. The crappy bridgestones that i have that are probably a large part of it. tire data for this car especially for handling is few and far between. i may just suck it up and go back to the pzero's instead of putzing around trying to find a "better" tire.

peet

Anyone else with 275 care to speak up on this subject? I hope that is not the case as I just ordered a set Though Savoy - you mention that traction is coming on which leads me to believe that you're slipping rather than sticking - if that is the case, the size is probably unrelated.

HELP!

BFNYM156

I just put on the Dunlop Direzza Sport Z1 Star Spec,235/40/18 front and 265/35/18 rear. Good tires, very sticky, feel even a bit quieter and softer than the Pzero. 265s fit the rear nice. 275 will be just fine, M3 have 265 PS2 tires in the rear, our cars need some fatter and sticky rubber

soldier2304

Tomorrow i'm getting a new set of tires and was gonna go 275 in the rear but now i see this thread and makes me wanna go bak to 265 again... If anyone can chime in that has used 275's wud be great...

Even Money

If you want 275s then you really need a 10" rim. Otherwise, you'll likely have handling issues.

jarjoug

I changed to 275 on the original rims, no problems what so ever on dry roads. I had some handling problems on some rainy days. I will go with 265.

George

peet

Well that settles that - between you guys and Gavin at the Tire Rack (great guy! no offense to Luke) I'm going 265. The biggest seller to me was the fact that the sidewall is taller - not a lot but this is almost 2 tons going on 450 torque after all.

Earlyapex

I put a set of 245's on the front and 275's on the rear (toyo RA1's). I have had the car on a road coarse and it handled great. The wider fronts help reduce the understeer which is still a problem in the slower corners. The tires also lasted longer than the stock tires eventhough they are R compound and were used for a track day.

pmknapp

Think I should stop reading these post, you guys make to much sence and what you say about the tires are great comments. I have 275 rears and 245 fronts. All Egale F1, and I must say that I have not noticed any handling issues on the car as of yet. Although maybe I do not drive like others do, I only do 145mph on a daily basis and yes there are a few long sweeper turns in there, and the car handles great. I understand the taller tires with stock rims does throw off the odometer (need to add 1 mph) at all speeds above 7mph as based on radar gun. I agree with Earlyapex, that the car handles better in my opinion, and he has a better tire than mine. Personly I will remain with 275 and 245 setup until otherwise can see a big differeance. Like I say I do not drive the car like others here do, but I have 37,000 miles on it and most of it is hard driving, and having gone to Egale F1 I have put so far 13000 miles on the rear set. So for me the cost differeance vs. the handling to me is far outwieghs going back to lower width tires. I will be replacing all the suspension setup and tires and brakes soon, complete change to the car, but for now I have had ZERO problems with the wider tires and they do last longer as well. With agressive track runs, and hard cornering on these tires and stock rims, there is also no body rub and the handling is great. I am no Formula 1 driver so I do not push it as such and really do not want to pull the car out of the baricades, so do back off a little in the turns, but I have no complaints and will remain with wider tires. For me its cost effective and handling is very adiquite as well.I can run down the phyisics of the tires and compair them all, and back it all up with proven data, but you guys here are better at that then I am, so I will not go into that. All I say is do what your heart and foot tell you to do and for me I stay with my current setup until I change it over the "off season" for next year. I love the way it is now, sure can be better, could be a McLaren Mercedes, but for now we make do with what we have.
Follow your foot and heart, try and experiment, with tires they do not last long and after they wear out change to different type and or size and experiment to your own driving abilities and likes.

Strafe1

No problems with the Nitto NT05's, 275's on the rears. Keep in mind that a 275 in one brand is not the same for all brands. I would not go to a smaller tread width than I have now because the improvement is too good.

deaguero

peet:

I have the 275x35x18's on the rear in the Toyo T1R's

I love them. They handle better and reduce the spin dramatically too.

I will be going to 245x40x18 Toyo T1R's in the front shortly to match the rear diameter.

Just my opinion!

Good luck!

Phil

yaymitch

Ditto

Also stayed with 235's on the front.

hhughes1

Did you use the RA1's for daily driving? They seem to be a great track tire but the price($400/corner) seems steep for a street tire with only ~5,000 miles of longevity. I was considering both the R1R and T1R as a compromise.