Upgrading to 245 size for front tires...
Thread Starter
Rennlist Member
Joined: Jul 2009
Posts: 5,970
Likes: 114
From: Vancouver, BC
Upgrading to 245 size for front tires...
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
- 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
Rennlist Member
Joined: Apr 2007
Posts: 8,578
Likes: 1,116
From: Florida
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
- 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
Three Wheelin'
Joined: Jan 2007
Posts: 1,797
Likes: 358
From: Central Massachusetts
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.
Rennlist Member
Joined: Apr 2007
Posts: 8,578
Likes: 1,116
From: Florida
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
Instructor
Joined: May 2011
Posts: 134
Likes: 0
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.
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Rennlist Member
Joined: Jun 2004
Posts: 620
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From: Sydney Australia
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
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
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AutoX
Joined: Nov 2011
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Ground clearance
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
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
Rennlist Member
Joined: Mar 2006
Posts: 6,570
Likes: 89
From: Austin
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%
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%
Race Director
Joined: Mar 2006
Posts: 15,362
Likes: 199
From: Tampa
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.
However just for street use and street driving you'll never know or feel the 235 vs 245 difference.
Rennlist Member
Joined: Jun 2001
Posts: 9,702
Likes: 1,311
From: Ohio
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.
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.