changing tire profile size dangerous?
 

Hello wheel experts of the 370z forum.

I am thinking about buying track rims for my 370z that I would put on before track events and drive to the track with and back. I think I have settled on 18 inch rims with the offset of 18x10 +34. I want to run 285 ad08's on these rims but these tires only come in a profile of 30.

I used the tire calculator and it said it was too much of a difference and would be dangerous for braking. Thus in short I am asking if this is true if so, it would completly negate the reason for me getting track rims, to get faster on track and save a little cash in the long run, if my brakes dont work well then tracking just isnt that fun anymore...

So can anyone give me their opinion or experience with running lower profile tires than the sports package 19inch rays?

Thanks in advance!

What calculator are you using? In theory, it's possible that the brakes will get hotter with the smaller wheel. But the calculator can't account for the design differences in wheels...

Tons of people run 18s on their 370Zs for the track, I wouldn't sweat it. What wheels and tires are you thinking about?

your speedo will be slightly off, and effective gearing shorter. With a 285/30/18 it won't be that problematic though. My SSRs have a similar tire profile.

I ran 285/30/18 (sold it to another forum member). Your speedo will be off by about 5mph. Car will feel like it gained an extra 50hp. In my case, more wheelspin and hop since it is so much less to spin. Other than that, nothing dramatic. You would probably need to disable the VDC.

im strongly considering the forgestar f14 in orange ( Im dutch so I have to represent my country!). The vdc is always off cossie it bites far too early than I want so that will never be an issue.

the tire size calculator i am using is the one from 1010 tires.

I run
265x30x19 front
295x30x19 rear

car feels great on the track. A little higher RPMs of course but braking is fine now that I found a good setup (pads, fluid, rotors).

I have short and tall tires on 2 different sets of wheels. The "short" tires have great acceleration due to the shortened gearing. I haven't noticed any braking issues as long as front and back are kept a similar diameter.

well id be purchasing square rims so i can rotate the rims w/ tires to get the most use out of them. so all four corners would be running 18x10 + 34 with 285/30/18 inch rims. SO the opinion is that it should work?

Yes.

I forgot to mention that the only thing I hate about the 285/30/18 (might have been 295/30 F&R, honestly dont remember). The car sits way too low for my liking. It would rub at every little incline

Are you lowered cossie?

check load ratings and if they are similar to the RE050A's or the Yok's you get on the 18's you're fine.

No, but the car rode more than an inch lower with the smaller tire.

One of my sets of wheels is exactly what you are looking at. 18x10+34 F14s with 285/30-18 AD08s all around. The other is even smaller with 275/35s. The speedo is off by about 10% and you will need a 15-25mm spacer in the rear, but other than that, no issues.

So is the speedo going to read higher or lower than the actual speed? Getting lower profile tires myself, but not as dramatic of a drop. 50 -> 40 for the front and 45 -> 35 for rear.