I seem to remember someone once saying that the larger the wheel, the less aggressive of an offset you can run. I am assuming it would be minimal, but if a 19x9.5 et35 is a nearly perfect offset for the rear, would a 20x9.5 et 35 be too much. Either way, would running a 265 in the rear reduce the chance of rubbing (noticed many people are starting to go with 275s)

Brandon

 

That is NOT a rule.

If you want to retain the same overall wheel/tire diameter as stock, as you increase the wheel diameter, you decrease the sidewall height. However, it is often impossible or impractical go with a tire with thinner sidewalls so most of the time using a larger wheel will result in using a tire that would cause an overall increase in diameter for the wheel/tire. So there is an IMPLIED relationship that as you increase wheel diameter, you will need to compensate the clearance issues by using higher wheel offsets.

Increasing the overall diameter of the wheel/tire combo reduces the amount of fender gap, therefore reducing tire/fender clearance and requires you to push the wheels in a bit more via higher offsets (but keeping in mind you need to clear the suspension components too!). This is assuming you are not changing the suspension height and only having 1 driver as the load under normal driving conditions (if you're auto crossing your car then you'll be compressing your suspension more which requires more fender clearance!).

If you're planning to use 265/30R19 on 19x9.5 ET35 it should fit the rear no problems on stock height with 1 driver (if you lower your car then you might need to use higher offsets and/or narrower tire like 255/30R19 where the wider wheel would stretch the sidewall a bit more thus producing a shorter overall sidewall height). If you're using 265/30R20 on 20x9.5 ET35 it would be 1" taller than he 19" combo and you have 0.5" less fender gap clearance which may cause rubbing. You would either have to consider a higher offset for the 20x9.5" or use a shorter tire like 265/25R20 or 275/25R20 assuming that these tire specs exists.

As you can see, suspension ride height (includes static height and compression under load which influences the amount of negative camber), wheel width, wheel offset, tire width, tire side wall height, are all factors contributing to whether a wheel/tire combo would fit/rub.

For 19x9.5" application for the rear, i would recommend ET40 with a 255/30R19 tire. This is a conservative setup and depending on your suspension mods/passenger load you can play with the offset and tire sizes (which also varies from different makes & models) accordingly.

confusing enough? yes. But when speaking about which tire/combo fits we need to consider ALL of these factors otherwise it can be misleading