alexb76

Can ppl who moved up a size upfront to 245 let me know the impact it's had?

- Handling? Street or track... I assume less understeer. But does it REALLY improve handling? as the car's suspention is desinged for 235/305.
- Ride? What impact the higher sidewall has?
- Fit? Does it fit ok with no scraping?
- Any changes in speedometer readings?
- Any ill effects, issues that one should watch out for?

Thanks

sandwedge

I never did move up but thought about it just like you are. Decided against it because the Bridgestone REO50 245 fronts are a full inch taller in overall diameter than the 235's. Not a big deal for everyday driving perhaps but elevating the front end by a 1/2" in exchange for a fraction of rubber width didn't do it for me. Other tire brands may have different configurations though.

Bijan

I guess the width difference will be 245 - 235 = 10 mm
The height difference will be 245 X profile % less 235 X profile % in mm

JW911

I think your math is flawed. The overall height would change by .2755 inches or just a hair more than 1/4 inch. The width would change by .39 inches or approximately 7/16 of an inch.

sclemmons

I would think you could accomplish much of what you are looking for by adjusting the air pressure on the tires you have.

sandwedge

If the 245 tire is an inch larger in diameter (top to bottom), how does that translate to only .2755 inches taller off the ground when mounted?

As for the width, I'm only going by Tire Rack's specs which show identical section width between the 235/35ZR19's and the 245/40ZR19's (REO50A).

http://www.tirerack.com/tires/tires....Without%20TPMS

AYHSMB

Actual tire sizes do not match the nominal size by a pretty large margin. I dunno about Bridgestone RE050's but it's quite possible that the real world difference is 1 inch.

Bijan

235 X 35% gives a theoretical wall height of 82.25 mm
245 X 40% gives a theoretical wall height of 98 mm
Difference is 15.75 mm or 0.62 inch, so diameter difference would theoretically be 1.24 inch
According to the tirerack table difference is (26.9 - 25.5) 1.4 real world inches, assume with some rounding to one decimal place

elliot_holeer

Interesting.....

Reading this, I've had a brain wave, and this could solve one of my biggest bug-bares with my car - Ground clearance.

I've got the areo kit on my 997, and my driveway is on a slight incline, at the moment i'm having to run it with a modified front splitter to ensure it doesnt get ripped off everytime I put it away in garage.

The clearance is current about an inch off what I'd need it to be to get on drive with an unmodified splitter.

Has anyone on here done this? If so, visually what does it look like. Is the increase in side wall size very noticable? Likewise, any impact on handling?

Thanks

kosmo

if you go to 245s stick w/ 35 series just like the gt2 rs which has 245/35/19.

jhbrennan

Here's the comp between 235 and 245 using the calculator from www.1010tires.com. The table layout is a little funky but first number is for 235, the second is for the 245 -


Stock Tire - 235/35R19 >Search Tires Tire 1 - 245/35R19 >Search Tires
Section Width: 9.25 in 235 mm
Section Width: 9.64 in 245 mm
Rim Diameter: 19 in 482.6 mm
Rim Diameter: 19 in 482.6 mm
Rim Width Range: 8 - 9.5 in
Rim Width Range: 8 - 9.5 in
Overall Diameter: 25.47 in 646.93 mm
Overall Diameter: 25.75 in 654.05 mm
Sidewall Height: 3.23 in 82.042 mm
Sidewall Height: 3.37 in 85.598 mm
Radius: 12.73 in 323.34 mm
Radius: 12.87 in 326.89 mm
Circumference: 80.01 in 2032.2 mm
Circumference: 80.89 in 2054.6 mm
Revs per Mile: 816.6
Revs per Mile: 807.7
Actual Speed: 60 mph 100 km/h
Speedometer1: 59.3 mph 98.9 km/h
Speedometer Difference: - Speedometer Difference: 1.101% too slow
Diameter Difference: - Diameter Difference: 1.09%

Bijan

kosmo and jhbrennan are right, if both are /35 then the diameter difference is about 1/4 inch

Edgy01

I'm not sure that I would consider a 245 front an UPGRADE over a 235 (stock).

mdrums

If you really want to take advantage of the 245 size you will need a 9x19" wheel...just like the GT3RS and GT2 RS come with. Rim width make a difference. It's much better to stretch the side wall a tiny bit and run the max rim width you can. This keeps the side wall and tire from moving around on you lateraly.

However just for street use and street driving you'll never know or feel the 235 vs 245 difference.

Alan C.

I put 245.35.19s on 8.5.19s front with 305.30.19s on 11.5.19 rears. Tires are MPSSS.

I can't tell any difference on the street. It probably gives a bit more grip on the track but it is hard to say. The car handled well at Putnam, Mid-Ohio and Watkins Glen. Other mods are in my signature.