Just switched to IS350 18's on my AWD 250. Questions regarding tire pressure light.
10-31-11, 04:16 PM
#16
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IIRC, optional 18s for the IS350 are 18x8 in the front and 18x8.5 in the rear, since the tires are stretched, the diameters of the front wheel would be different from the rear wheel since you have 225/40/18s all around. The rears being stretched would make the diameter smaller than the fronts, which I don't know how much smaller, but its a no-no for AWD system
10-31-11, 07:47 PM
#18
Hey kurtz , I ve been contemplating on if i should run staggered on my AWD and I figured i would give it a try once i get correct tires. Since you seem to be one of the most knowledgeable people on here I wanted to ask for your opinion on the issue if you get the correct size. Im looking at a difference of +0.08% in the rear
).... That said, 0.08% is pretty durn close to even...my opinion you'll be about as fine as you can be running staggered and wouldn't worry too much about it... (though if you're still under warranty the dealer is likely to note the tire setup, and might try blaming any future drivetrain issues on it)IIRC, optional 18s for the IS350 are 18x8 in the front and 18x8.5 in the rear, since the tires are stretched, the diameters of the front wheel would be different from the rear wheel since you have 225/40/18s all around. The rears being stretched would make the diameter smaller than the fronts, which I don't know how much smaller, but its a no-no for AWD system
Width != diameter
http://www.miata.net/garage/tirecalc.html
That'll compare rolling diameter of wheel/tire combos... note it never asks for the width of the rim, just the diameter of it.
If that's not enough for ya, how bout Tire Rack?
http://www.tirerack.com/tires/tirete...jsp?techid=200
Originally Posted by TIre Rack
A tire's section width (also called "cross section width") is the measurement of the tire's width from its inner sidewall to its outer sidewall (excluding any protective ribs, decorations or raised letters) at the widest point. This measurement is made without any load placed upon the tire and after the tire has been properly mounted on its industry assigned measuring rim and has been inflated and reset to its test pressure after 24 hours.
Because a tire's section width is influenced by the width of the rim upon which the tire is mounted, the correct industry assigned measuring rim width for the tire size being measured must be used.
The width of a tire mounted on a narrow rim would be "narrower" than if the same tire was mounted on a wide rim. NOTE: because the overall diameter of a steel belted radial is determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.
The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".
Because a tire's section width is influenced by the width of the rim upon which the tire is mounted, the correct industry assigned measuring rim width for the tire size being measured must be used.
The width of a tire mounted on a narrow rim would be "narrower" than if the same tire was mounted on a wide rim. NOTE: because the overall diameter of a steel belted radial is determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.
The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".
10-31-11, 08:12 PM
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Great input Kurtz. I ordered 255/35/18 and I think the difference was less than .05 with those tires paired with the 225/40's up front. I think it'll look better than the 255/40's also. We'll see.. I've driven it this way for 3 days now and I'm sweating it out until my new tires arrive.
10-31-11, 10:35 PM
#22
the stretch is very minimal, you would have to be really close to notice it, im not sure what tedward88 is trying to say, isnt rolling diameter measured by tire size not rim size? Are you saying my rolling diameter is way off? im pretty sure it is the same or damn close, but if you disagree please correct me and tell me why because i was told by some people who work at tire shops that this set up would be ok, dont want any long term damage to my AWD ( even tho i might not be keeping it)
10-31-11, 11:18 PM
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I'm saying the width of the wheel would stretch out the tires if your using the same tire size all around while having different wheel width sizes, but i guess im wrong according to kurtz
11-01-11, 06:35 PM
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I have the same rims on my 07 IS250 AWD. I was running 225/40-18 on the front and 255/40-18 on the rear with no problems. I did switch the back tires to 265/35-18 which brought the tire to less then a quarter inch difference. There is a whole thread on this https://www.clublexus.com/forums/is-...er-thread.html check it out. That's where I did some of my research.
11-01-11, 08:27 PM
#27
stock IS350 wheels are 225x40x18 with 18x8 rim front
255x40x18 with 18x8,5 rim rear
so if you wanna run it with the same size of tire like in front, i don't think it will cause any problem on your awd ride since your using the same size of tire,the only difference on the wide of the rim is 0,5- will not cause a huge difference or none,rear will look only a little stretch
255x40x18 with 18x8,5 rim rear
so if you wanna run it with the same size of tire like in front, i don't think it will cause any problem on your awd ride since your using the same size of tire,the only difference on the wide of the rim is 0,5- will not cause a huge difference or none,rear will look only a little stretch
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