This is my first winter in Michigan, and I was looking to get some snow tires for my IS350. It has 18" wheels. I talked with someone at Tire Rack and he ordered Bridgestone Blizzaks, 225/40R18 for the front and 225/45R18 for the rear. Does that make sense? I know they need to be staggered, so I'm wondering whether this works. The recommendation on the website is 225/40R18 and 255/40R18. Any help would be greatly appreciated since I don't really know much about tires. Thanks!

uva2008

 

you can stretch a 225 on your rear 9.0" wide rim, but thats at the max of what the mfr recommends. its safe, but beyond 9.0 its not.

having said that, go with a 235 or 245

 

You need 255/40/18 for the rears

the 255 is the width, 40 is the height (40% of the width), and 18 is your rim size. By getting a 225/45/18, all you are doing is getting a taller version of your front tire.

also, 255/40/18 is the size lexus recommends as stated in the manual.

 

Hmm, looks like 2 different opinions, 1 that it will work and 1 that it won't. I called someone else at Tire Rack and they said the original guy did the right thing and said something about it being narrower and therefore better on snow and ice. I'm really confused here. Even Tire Rack's own website recommended the 225/40R18 and 255/40R18. But both guys that I talked to said the 225/40R18 and 225/45R18 are better.

Thanks for the quick responses so far. I'll have to let them know before tomorrow morning if I need to cancel or change the order.

 

235s will be fine dude....

 

And 225/45 for the back? Thanks. (Sorry for the utter lack of knowledg about this).

uva2008

 

i wouldnt....

if you HAVE to go narrower, which I dont know why you would, 245/40/18 will work for the rears

Remember, swaying too far from OEM tire diameter will make your speedo and odometer off a little as well...

 

For snow tires, narrower is better. You can read up on it.

What he says is right, don't sway too far from OEM, if what that one guy says is true, if 225 is ok by the manufacturer, then it's fine to put on your car.

 

Actually, i just looked looked it up, and 225/45 might work, it's not as off as I thought it would be:

Stock Tire - 255/40R18******** >Search Tires Tire 1 - 225/45R18******** >Search Tires
Section Width: 10.03 in 255 mm
Section Width: 8.85 in 225 mm
Rim Diameter: 18 in 457.2 mm
Rim Diameter: 18 in 457.2 mm
Rim Width Range: 8.5 - 10 in
Rim Width Range: 7 - 8.5 in
Overall Diameter: 26.03 in 661.16 mm
Overall Diameter: 25.97 in 659.63 mm
Sidewall Height: 4.01 in 101.85 mm
Sidewall Height: 3.98 in 101.09 mm
Radius: 13.01 in 330.45 mm
Radius: 12.98 in 329.69 mm
Circumference: 81.77 in 2076.9 mm
Circumference: 81.58 in 2072.1 mm
Revs per Mile: 799.0
Revs per Mile: 800.9
Actual Speed: 60 mph 100 km/h
Speedometer1: 60.1 mph 100. km/h
Speedometer Difference: - Speedometer Difference: 0.237% too fast
Diameter Difference: - Diameter Difference: 0.24%

 

i put 225/40/r18 on the front and rear. that was suggested for me to keep them all the same size in the snow. you get better performance.

 

I understand the keeping the front and rear the same, so I would have done 235's or maybe 245's all around. Blizzaks are ALREADY narrower then regular tires. Like a 225/45 blizzak is more narrow then a 225/45 bridgestone. You'll see, that thing is gonna be major stretched on the rear wheels. I would have maybe done a 245/40 in the rear, but def not a 225/45

 

I need to get snow tires for my 2008 IS 350 also.

When I put in my 2008 IS 350's size in tirerack.com, the only options I get are the 225/40R18 & 255/40R18 Blizzam LM-60, Blizzak LM-60 RFT, and the Dunlop SP Winter Sport 3D. But looking at this thread, seems I can go with different sizes and I'm that would get me more options.

Looking at the post right above from RpmSteve, seems 235s or 245s are the best way to go all around - especially if going with blizzaks.

I'm using the original rim. It would be nice to have the same tires for ease of rotation and replacement if need be, but how would my performance be affected?

I'm going to take my summer Bridgestone ER33 tires off and mount the winter ones on the original rim. Next Spring I'll put the ER33s back and and probably finish them off. The car's currently at 17k miles (it was bought new in Jan) and the tires are at 5/32 in the rear and 6/32 in the front.

Maybe next year I'll get some winter wheels to make everything easier, but I do like mounting and remounting on stock rims because a) I really like the way they look, b) I like that I have the ability to work a balance in during the mount and c) move the tires to different sides when they're put back on.