please help!!!

[kentchoi]

I bought a set of lexus chrome 18", 7.5" wide, 45 mm offset, 5X4.5 same as 5X114.3 bolt pattern to fit a lexus sc400. Would someone please help explain the maximum tire size(width) i can mount....I tried to read up on information and what i believe is that I can fit a 225/40/18 tire
NOT a 235/40/18 or 245/40/18 right?

SOMEONE PLEASE GIVE ME SOME EXPERT ADVICE!!!
THANKS FOR THE INPUT!!!

[Grant@Tirerack]

The 225/45-18 is the only size that will fit that narrow of a rim. Those are very narrow (7.5") for that car. You would want to stick with a 45 series as well. The 225/40-18 is going to be 7/10" shorter than the stock size and will not have enough load capacity to work safely.

[kentchoi]

Grant you seem to be very popular and knowledgable. The 40 will be dangerous then??? You mean that the rims might hit the road if i hit a sharp bump or what do you mean??? thanks for the input though...

[email protected]

[Grant@Tirerack]

The main issue is the air chamber size. Dropping to a 40 series gives you a much smaller air chamber and you can't get enough air volume to support the weight safely. Any time you decrease the air chamber size or the air pressure, you limit the tire's ability to support the weight of the vehicle. The over loaded tire will have more bulge in the lower part of the sidewall (down by the ground). As the tire rotates, the bulge in that section of the sidewall flattens out as it rotates away from the ground and bends back again as it rotates down again. That flexing builds up heat (just like when you bend a paperclip back and forth, it heats up). It does not take that long for the temp in the sidewalls to reach the temps they use to cure the layers together when the tire is built. That's why you see lower profile tires that are overloaded with bubbles in the sidewalls. They are over worked, they overheat faster in the Summer, and they are more prone to impact damage because the sidewalls are over stressed and break down faster.

[kentchoi]

The 1993 sc 400 weighs 3495 lbs. obviously a little heavier than the v6 sc300

I was planning on the 225/40/18 but if your expertise says otherwise I will go with the 45's

any knowledge of how it might look/feel/rife/handle...also do you recommend z rated tires as a must or will a lower speed rated tire feel close to the same???

thanks for the response...

kent

[Grant@Tirerack]

You would pretty much be looking at a Z rated tire in these sizes. I would look at the Yokohama AVS ES100 in that size for the best in an ultra high performance tire. In a max performance, I would look at the Bridgestone S03 Pole Position or the Michelin Pilot Sports.