mdfdsc300

Looks like I might need new tires. I've got some Fittipaldis 17x8.5" w/ 235/45 SZ50s for my '92 SC300. What's the widest tire I can go with to fit my rims and stay within spec for overall factory diameter?
TIA!

Manaray

You can go 245/45-17 on that wheel. Any wider of a tire, you're going over the recommended tire width for a 8.5" wide wheel...

mdfdsc300

but wouldn't 245/45 take me out of the acceptable variance from overall stock diameter?:eek:

MrWigggles

You could put a 255/45 on the wheel without any problems, but I think that 245/45 is a better size to go with.

It will be the correct overall diameter.

-Mr. Wigggles

Manaray

Well here's the deal, even though you have a 300, you can us a 400 size tire...the stock SC400 gets 225/55-16

A '92 SC300 came with 215/60-15...they're too small, which is why in '95, Lexus upped it to the same size as the SC400 (225/55-16)

So here's the break down in diameters...

215/60-15 = 25.1575" (Stock '92 SC300)
225/55-16 = 25.7441" (Stock '95+ SC300 and '92+ SC400)

Right there, the 16" is 2.28% larger...now for the 17...

245/45-17 = 25.6811

Compared to the 225/55-16, it's 0.25% smaller and compared to the 215/60-15, it's only 2.08% larger.

So you can see that even if you put on FACTORY '95 and up GS300 wheels, you'd be increasing the diameter MORE than doing the 245/45-17 setup...

Now if you go with the 255/45-17, you talking about a 26.0354" diameter...which is 3.49% more than the 215/60-15 and 1.131% more than the 225/55-16 tire...and you're 1.38% more than the 245/45-17...

Plus, a 245 fits a 8.5" wheel properly. 255's are designed for 9" wheels...

Hope that helps...

mdfdsc300

I was under the impression I needed to stay within 1% of original factory diameter (25.175"). When Lexus upped the factory wheels to 225/55/16 did they make any adjustments to align the speedo?

I may just end up going 245/45/17. I'm actually afraid of loosiing what low end grunt my car has now by going w/ a larger overall diameter....