Need Advice Regarding Tire Diameter Stagger Front/rear

denniscasey · October 10, 2011

My 2007 IS350 with 18 inch wheels has considerable tire stagger front/rear--OEM front tire diameter in 25.08 inch, rear tire diameter is 26 inch. I want to put studdable snow tires with 25.1 inch diameter on front and 26.7 inch diameter on rear. This could result in headlights being aimed high except I recall reading somewhere that headlights on car can adjust to changes in car "angle" (for instance if you have heavy load in rear--passengers, luggage, etc)so they are not aimed too high (dazzle oncoming cars). Is difference in tire diameter front/rear I want to put on vs OEM front/rear too much for headlight aiming to compensate for? Can dealer "adjust" headlights to compensate--used to do this headlight aiming in old days? Could I have other problems in deviating from OEM front/rear diameters?

Reason for wanting to do this is to get matched set of Blizzaks on car. Recognizing tire choice varies with everyone's needs I have tried other types of snow tires and Blizzaks for me are what I want--I am not "performance" driver in winter--save that for when I have performance tires on car. Other option is to put Blizzak WS60 on front and WS70 on rear--this will match OEM front/rear diameter stagger but might possibly give strange handling?

Appreciate your experience input, thank you.

1990LS400 · October 10, 2011

I went from Blizzak WS50 to WS70 where the tread design was completely different. If I remember correctly, there isn't as much difference between the WS60 and WS70 with both being directional tires unlike the WS50. I think I remember that WS70 has a slightly narrower tread in some of the corresponding WS60 sizes where the same size was available in both models. I say "was" because a Bridgestone representative told me that the WS60 was going to be continued in some sizes but that the WS70 replaced the WS60 in others. By the way, I was amazed how helpful the Bridgestone representative was when I asked about the WS70 several months before they went on sale and before the specs were made public - they emailed me an advance copy of the specs for all sizes.

I wonder if your car would be too "tail happy" if you got a set of the 17" OEM wheels that were standard on the 07 IS350 and then put 225/45-17 Blizzaks all around. Your car's electronic gizmos (e.g. VSC) should still help prevent spinning out unless you get too crazy.

And 17" Blizzaks would likely cost substantially less and last longer than 18" Blizzaks on your current wheels.

Maybe look for a set of used 17" OEM wheels on Craigslist or see if your dealer has some. I bought a set of new "take off" OEM wheels from the local Lexus dealer 21+ years ago and the dealer sold them to me very cheaply - but of course I had just bought a new LS there.

Each November when I put snow tires on my LS, it's like I turn a switch in my brain and completely change my driving style for four months -- no more screaming around interstate cloverleafs at the limits of adhesion.

If you do what I'm suggesting, you might have to sign a release at an installer/tire seller since the rear snow tires would be narrower than standard. I was surprised that Costco had me sign a release when I bought a set of H-rated Michelin all season tires -- the car came with V-rated tires. Did they think I was going to exceed 130 mph? Oddly, Costco didn't require a release when I bought the T-rated (118 mph) WS70's for my LS.

denniscasey · October 11, 2011

Thank you for input, Jim. By the way, I had typo in my original post option 1. I meant 25.7 inch rear tires not 26.7 inch rear tires--that would lower rear end slightly from OEM. Subsequent to my note I talked to a Lexus service manager and he said headlights would adjust to lower rear end--would not be a problem. So I have two options: (1) WS60 all around on 18 inch wheels leaving back end 0.3 inches lower than OEM; (2) WS60 on front and WS70 on rear to retain OEM tire diameters front and rear--and I don't think different tread pattern WS60 and WS70 would affect handling too much under cautious winter driving I do.

You mentioned different wheels--IS350 does come with 17 inch wheels or 18 inch wheel option on my IS350. I did investigate 17 inch wheels on front and leave 18 inch wheels on rear. With that combination I can get WS70's all around in combination that maintains OEM diameter front and rear. But, overall cost (wheels plus new tire pressure monitors) goes up $450 (Tire Rack low cost wheels) vs just getting tires. Dennis